Particle separator filter with an axially extending flow face

ABSTRACT

A two-stage separator system having a housing extending between a first end and a second end. The housing defines a housing inlet, a separator outlet towards the second end, and a filtration outlet on the first end. A filter assembly has a first sheet of filter media coupled to a second sheet of filter media mutually defining a plurality of flutes extending in an axial direction. The filter assembly defines an inlet flow face and an outlet flow face. The filter assembly is disposed in the housing and coupled to the housing about the filtration outlet such that the outlet flow face is in fluid communication with the filtration outlet. The inlet flow face of the filter assembly has an axial flow face length.

The present application claims priority to U.S. Provisional PatentApplication No. 62/824,812, filed on Mar. 27, 2019, which isincorporated by reference herein.

TECHNOLOGICAL FIELD

The present disclosure is generally related to a particle separator.More particularly, the present disclosure is related to a particleseparator with an axially-extending flow face.

SUMMARY

Some embodiments of the current technology relate to a two-stageseparator system. A housing extends between a first end and a second endand defines a housing inlet, a separator outlet towards the second end,and a filtration outlet on the first end. A filter assembly is disposedin the housing. The filter assembly has a first sheet of filter mediacoupled to a second sheet of filter media mutually defining a pluralityof flutes extending in an axial direction, wherein the filter assemblydefines an inlet flow face and an outlet flow face. The filter assemblyis coupled to the housing about the filtration outlet such that theoutlet flow face is in fluid communication with the filtration outlet.The inlet flow face has an axial flow face length.

In some such embodiments, a radial distance is defined between the inletflow face and the housing, where the radial distance increases for atleast a portion of the axial flow face length from the first end towardsthe second end. Additionally or alternatively, the filter assembly hasan outer radial barrier surface extending axially from the filtrationoutlet beyond the housing inlet. Additionally or alternatively, thefilter assembly has an outer radial barrier surface having an axiallength from the outlet flow face that is greater than or equal to anaxial distance from the filtration outlet to a distal end of the housinginlet.

Additionally or alternatively, the housing inlet defines an airflowpathway that is tangential to an outer radial barrier surface of thefilter assembly. Additionally or alternatively, at least a portion ofthe outer radial barrier surface is defined by the first sheet of filtermedia. Additionally or alternatively, the inlet flow face defines ataper for at least a portion of the axial flow face length from thefirst end towards the second end. Additionally or alternatively, thetaper increases for at least a portion of the axial flow face lengthfrom the first end towards the second end. Additionally oralternatively, the taper continuously changes along the axial flow facelength from the first end towards the second end. Additionally oralternatively, the taper continuously increases along the axial flowface length from the first end towards the second end. Additionally oralternatively, the first sheet of filter media is a facing sheet and thesecond sheet of filter media is a fluted sheet. Additionally oralternatively, the first sheet of filter media and the second sheet offilter media define a coiled configuration about a z-axis extending inthe axial direction.

Additionally or alternatively, the system has a rod extending centrallythrough the filter assembly, the rod having a proximal end positionedtowards the outlet flow face and a distal end positioned towards theinlet flow face, and the system has a rod receptacle defined by thesecond end of the housing, where the rod receptacle is configured toreceive a distal end of the rod. Additionally or alternatively, distalend of the rod defines a handle. Additionally or alternatively, thefilter assembly has a circular cross-section. Additionally oralternatively, the filter assembly has a plurality of first sheets offilter media and a plurality of second sheets of filter media in analternating, stacked configuration and a radial sleeve disposed aboutthe stacked first sheets of filter media and second sheets of filtermedia. Additionally or alternatively, the housing inlet is definedtowards the first end of the housing.

The above summary is not intended to describe each embodiment or everyimplementation. Rather, a more complete understanding of illustrativeembodiments will become apparent and appreciated by reference to thefollowing Detailed Description of Exemplary Embodiments and claims inview of the accompanying figures of the drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

The present technology may be more completely understood and appreciatedin consideration of the following detailed description of variousembodiments in connection with the accompanying drawings.

FIG. 1 is a side view of an example two-stage separator systemconsistent with the present disclosure.

FIG. 2 is a cross-sectional view of a housing of an example separatorsystem consistent with FIG. 1.

FIG. 3 is a perspective view of an example filter assembly consistentwith the technology disclosed herein.

FIG. 4A is a perspective view of another example filter assemblyconsistent with the technology disclosed herein.

FIG. 4B is a detail view A′ of FIG. 4A.

FIG. 5 is a side cut-away view of another example filter assemblyconsistent with the technology disclosed herein.

FIG. 6A is example filter media consistent with some embodiments.

FIG. 6B is another example filter media consistent with someembodiments.

FIG. 6C is yet another example filter media consistent with someembodiments.

FIG. 6D is an example filter media consistent with some embodiments.

FIG. 7 is a perspective view of another example filter assemblyconsistent with the technology disclosed herein.

FIG. 8 depicts a cross-sectional view of an example filter assemblyconsistent with the technology disclosed herein.

FIG. 9A is a perspective view of another example filter assemblyconsistent with the technology disclosed herein.

FIG. 9B is a facing view of a first face of the filter assembly of FIG.6 a.

FIG. 10 is a perspective view of yet another example filter assemblyconsistent with the technology disclosed herein.

FIG. 11 is a perspective view of yet another example filter assemblyconsistent with the technology disclosed herein.

FIG. 12 is a perspective view of yet another example filter assemblyconsistent with the technology disclosed herein.

FIG. 13 is a perspective view of yet another example filter assemblyconsistent with the technology disclosed herein.

FIG. 14A is a side view of another example filter assembly consistentwith the technology disclosed herein.

FIG. 14B is a facing view of filter media consistent with FIG. 14A.

FIG. 15A is a cross-sectional view of another example filter assemblyconsistent with the technology disclosed herein.

FIG. 15B is a facing view of filter media consistent with FIG. 15A.

FIG. 16A is a cross-sectional view of another example filter assemblyconsistent with the technology disclosed herein.

FIG. 16B is a facing view of filter media consistent with FIG. 16A.

FIG. 17A is a perspective view of another example filter assemblyconsistent with the technology disclosed herein.

FIG. 17B is a facing view of filter media consistent with FIG. 17A.

FIG. 18 is a side cut-away of a filter assembly consistent with thetechnology disclosed herein.

FIG. 19 is another side cut-away view of a filter assembly consistentwith the technology disclosed herein.

FIG. 20 is another side cut-away view of a filter assembly consistentwith the technology disclosed herein.

FIG. 21 is a cross-sectional view of filter media consistent withvarious embodiments.

FIG. 22 is a facing schematic view of a flow face of an example filterassembly consistent with the technology disclosed herein.

FIG. 23 is a cross-sectional schematic view of a filter assemblyconsistent with the technology disclosed herein.

FIG. 24 is a cross-sectional view of another example two-stage separatorsystem consistent with some embodiments.

FIG. 25a depicts a schematic of a first example cross-section associatedwith FIG. 2.

FIG. 25b depicts a schematic of a second example cross-sectionassociated with FIG. 14 a.

FIG. 26a depicts a schematic of a first example cross-section associatedwith a system incorporating a filter assembly similar to that depictedin FIG. 14 a.

FIG. 26b depicts a schematic of a second example cross-sectionassociated with a system incorporating a filter assembly similar to thatdepicted in FIG. 14 a.

FIG. 27a depicts a schematic of a first example cross-section associatedwith another example system consistent with some embodiments.

FIG. 27b depicts a schematic of a second example cross-sectionassociated with the example system of FIG. 27 a.

FIG. 28 is a cross-sectional view of yet another example two-stageseparator system consistent with some embodiments.

FIG. 29 is a cross-sectional view of an example standard two-stageseparator system consistent with the previous technologies.

The figures are rendered primarily for clarity and, as a result, are notnecessarily drawn to scale. Moreover, various structure/components,including but not limited to fasteners, electrical components (wiring,cables, etc.), and the like, may be shown diagrammatically or removedfrom some or all of the views to better illustrate aspects of thedepicted embodiments, or where inclusion of such structure/components isnot necessary to an understanding of the various exemplary embodimentsdescribed herein. The lack of illustration/description of suchstructure/components in a particular figure is, however, not to beinterpreted as limiting the scope of the various embodiments in any way.

DETAILED DESCRIPTION

FIG. 1 is a side view of an example two-stage separator system 1900consistent with the present disclosure. The separator system 1900 has ahousing 1910 that houses a filter assembly 1950 disposed therein. Thefilter assembly 1950 can be generally consistent with filter assembliesdescribed herein consistently with FIGS. 3-24.

The housing 1910 generally extends between a first end 1912 and a secondend 1914. The housing 1910 defines an interior volume 1916. In variousembodiments the housing 1910 extends in an axial direction defined by acentral axis z. The housing 1910 defines a housing inlet 1920, aseparator outlet 1930 towards the second end 1914, and a filtrationoutlet 1940 on the first end 1912. A filter assembly 1950 is positionedin the interior volume 1916. The housing 1910 is configured to receiveunfiltered fluid, such as air, through the housing inlet 1920, allowexpulsion of separated particulates through the separator outlet 1930,and allow filtered air to exit through filtration outlet 1940. Thisfunctionality will be described in more detail below.

In various embodiments, the housing 1910 has a main portion 1960 and anaccess cover 1970 that are detachably coupled. The main portion 1960 candefine the first end 1912 of the housing 1910 and the access cover 1970can define the second end 1914 of the housing 1910. The main portion1960 and the access cover 1970 are detachably coupled for removal andinstallation of a filter assembly 1950 through a second end 1962 of themain portion 1960. The access cover 1970 encloses the second end 1962 ofthe main portion 1960 of the housing 1910.

The main portion 1960 and the access cover 1970 are detachably coupledwith mutually defined mating features 1980. In the current example, theaccess cover 1970 defines a latch 1982 and the second end 1962 of themain portion 1960 defines a latch receptacle 1984, although otherconfigurations are certainly contemplated. For example, the main portion1960 and the access cover 1970 can define a mating threaded connection,a bayonet connection, and the like.

The housing inlet 1920 can be defined by a tubular structure 1922 (thatis not necessarily circular in cross-section) that extends outwardlyfrom the housing 1910. The housing inlet 1920 is defined by the mainportion 1960 of the housing 1910. In various embodiments, including thatdepicted, the housing inlet 1920 is a tangential inlet, meaning thatairflow through the housing inlet 1920 is directed in a tangentialdirection relative to the filter assembly 1950. In other words, in someembodiments the housing inlet is generally not directed toward thecentral axis z of housing 1910. Housing inlets 1920 having alternateconfigurations can also be used, however. In some embodiments, such asthat depicted, the housing inlet 1920 is defined towards the first end1912 of the housing 1910.

In the present example, the housing inlet 1920 is in fluid communicationwith an interior flow guide 1924, which is configured to receive fluidflowing into the housing 1910 from the housing inlet 1920 and direct thefluid in a spiraled flow path about the interior volume 1916 of thehousing 1910. The flow guide 1924 can be a ramp, deflector, wall,channel, or other structure extending from the housing inlet 1920 thatdefines a portion of a spiral flow path in the interior volume 1916 ofthe housing 1910. Some embodiments may lack a flow guide 1924. In someother embodiments a flow guide can be defined by the filter assembly1950, which will be described in more detail, below.

The separator outlet 1930 is generally defined by an ejector tube 1932that extends outwardly from the housing 1910. The ejector tube 1932 isdefined by the access cover 1970 of the housing 1910. The ejector tube1932 allows for expulsion of at least a portion of the particulatecontaminants from the unfiltered fluid during operation. In someembodiments, the ejector tube 1932 has an evacuator valve arrangement1934 to selectively evacuate the collected particulate contaminants.

The filtration outlet 1940 is defined by an outlet tube 1942 thatextends outwardly from the housing 1910. The filtration outlet 1940 isdefined by the main portion 1960 of the housing 1910. In the currentexample, the filtration outlet 1940 extends axially away from thehousing on the first end of the housing 1910.

In an example implementation consistent with FIG. 1, air enters thesystem 1900 through the housing inlet 1920, in a tangential direction tothe filter assembly 1950. The housing inlet 1920 directs the airflow tothe interior flow guide 1924, which guides the airflow along a spiraledpath about the filter assembly 1950 towards the second end 1914 of thehousing 1910. Such airflow can result in separation of at least aportion of the relatively larger particles in the air, which can havesufficient momentum to travel to the second end 1914 of the housing1910. The particles can migrate to ejector tube 1932 and be ejectedthrough the separator outlet 1930 via the evacuator valve arrangement1934.

The remainder of the particulate in the air that is not ejected throughthe separator outlet 1930 is directed through the filter assembly 1950by a vacuum force. The air is filtered by the filter assembly 1950 andexits the housing 1910 through the filtration outlet 1940 of the outlettube 1942 on the first end 1912 of the housing 1910. The filtered aircan then be directed to the relevant external system.

FIG. 2 is a first example cross-sectional view consistent with theseparator system 1900 of FIG. 1. The system 1900 can have the samecomponents, structure, and possible modifications as described above. Ingeneral, the housing 1910 extends between a first end 1912 and a secondend 1914 and defines a housing inlet 1920 towards the first end 1912.The housing 1910 defines a separator outlet 1930 towards the second end1914 and a filtration outlet 1940 on the first end 1912.

A filter assembly 1950 is disposed in the housing 1910, that isgenerally configured to filter air within the housing 1910. The filterassembly 1950 has an inlet flow face 1952, an outlet flow face 1954, andfilter media 1956 extending in the axial direction z. The filter media1956 extends between the inlet flow face 1952 and the outlet flow face1954. A “flow face” as defined herein is the side of the filter assemblythrough which fluid is configured to enter or exit the filter assembly.

The inlet flow face 1952 is configured to receive unfiltered air fromwithin the housing 1910. The outlet flow face 1954 is configured torelease air that has been filtered by the filter media 1956. The inletflow face 1952 and the outlet flow face 1954 are defined on oppositeaxial ends of the filter assembly 1950. In various embodiments filterassembly 1950 is configured such that fluid is limited to entering thefilter assembly 1950 in the axial direction. In various embodimentsfilter assembly 1950 is configured such that fluid is limited to exitingthe filter assembly 1950 in the axial direction. In some embodiments theoutlet flow face is planar, but in other embodiments the outlet flowface is non-planar, which will be described below with respect to FIGS.3-20.

The filter assembly 1950 is coupled to the housing 1910 about thefiltration outlet 1940 such that the outlet flow face 1954 is in fluidcommunication with the filtration outlet 1940. In various embodiments,the filter media 1956 surrounding the outlet flow face 1954 is coupledto the housing 1910 about the filtration outlet 1940. In the currentexample, the filter assembly 1950 has a potting feature 1953 that is aradial potting sleeve configured to receive a first end of the filtermedia 1956 about the outlet flow face 1954. The first end of the filtermedia 1956 can be coupled to the potting feature 1953 using adhesives,gaskets, compression fits, and/or through additional or alternativestructures. The potting feature 1953 and the first end of the filtermedia 1956 are configured to form a seal about the outlet flow face1954. In various embodiments, the potting feature can be sealed with anadhesive to the first end of the filter media 1956.

The potting feature 1953 is generally configured to form a sealedconnection between the outlet flow face 1954 of the filter media 1956and the filtration outlet 1940 of the housing 1910. In particular thepotting feature 1953 and the housing 1910 are configured to form asealed connection to isolate the outlet flow face 1954 and thefiltration outlet 1940 from the remainder of the interior volume 1916 ofthe housing 1910. The potting feature 1953 can be substantiallyimpermeable to airflow therethrough. The potting feature 1953 can beimpermeable to airflow therethrough.

In this example, the housing 1910 has a filter receptacle 1926 that isconfigured to receive the potting feature 1953 and the first end 1951 ofthe filter media. In some embodiments a radial seal can be disposedradially between an outer radial surface 1955 of the potting feature1953 and an inner radial surface 1927 of the housing 1910 within thefilter receptacle 1926. In some embodiments an annular axial seal can bedisposed between an annular surface 1957 defined by the potting feature1953 and a mating surface of the housing 1910 within the filterreceptacle 1926. In some alternate examples, the potting feature and thefilter receptacle of the housing can define a mating structure thataccommodates a radial seal between an inner radial surface of thepotting feature and an outer radial surface of the housing within thefilter receptacle.

The filter assembly 1950 has an outer radial barrier surface 1958between the inlet flow face 1952 and the outlet flow face 1954. In someembodiments, the outer radial barrier surface 1958 can be configured toguide airflow tangentially about the filter assembly 1950. In some suchembodiments, the housing inlet 1920 defines an airflow pathway that istangential to an outer radial barrier surface 1958 of the filterassembly 1950.

The outer radial barrier surface 1958 is generally configured toobstruct airflow into the filter assembly 1950 through the outer radialbarrier surface 1958. In some embodiments, at least a portion of theouter radial barrier surface 1958 is defined by filter media 1956 thatis a sheet of filter media. In some embodiments, the outer radialbarrier surface 1958 is defined by a separate sleeve disposed about thefilter media 1956. The sleeve can be constructed of a material having ahigher resistance to airflow therethrough compared to the inlet flowface 1952 of the filter assembly 1950, which can discourage airflowthrough the sleeve and, therefore, encourage spiraling airflow about thefilter assembly towards the second end 1914 of the housing 1910. Such aconfiguration can increase the efficiency of the separator. In someembodiments the sleeve is constructed of a cellulose material, in someembodiments the sleeve is constructed of a polymeric material.

The outer radial barrier surface 1958 has a length Lsurface extending inthe axial direction. The outer radial barrier surface 1958 can extendfrom the outlet flow face 1954 towards the inlet flow face 1952. Inexamples, the outer radial barrier surface 1958 is partially defined bythe potting feature 1953. As such, the length Lsurface of the outerradial barrier surface 1958 extends axially from the potting feature1953 to the inlet flow face 1952. In some embodiments, the lengthLsurface of the outer radial barrier surface 1958 is greater than orequal to an axial distance D from the filtration outlet 1940 to a distalend of the housing inlet 1920. The “distal end of the housing inlet” isthe furthest portion of the housing inlet 1920 from the filtrationoutlet 1940 in the axial direction. In some embodiments, the outerradial barrier surface 1958 extends axially from the filtration outlet1940 beyond the housing inlet 1920. Such a configuration encouragesspiraling airflow about the filter assembly 1950 towards the second end1914 of the housing 1910.

In some embodiments, the outer radial barrier surface 1958 can define aflow guide that is configured to receive fluid flowing into the housing1910 from the housing inlet 1920 and direct the fluid in a spiraled flowpath about the interior volume 1916 of the housing 1910. The flow guidecan be a ramp, deflector, wall, channel, or other structure extending atleast partially around the outer radial barrier surface 1958.

The inlet flow face 1952 of the filter assembly 1950 has a flow facelength L_(inlet) in the axial direction z. In some embodiments, theinlet flow face 1952 defines a taper for at least a portion of the axialflow face length L_(inlet) from the first end 1912 towards the secondend 1914 of the housing 1910. Such a taper can help encourage spiralingairflow about the filter assembly 1950 towards the second end 1914 ofthe housing 1910 and discourage settling of contaminants across theinlet flow face 1952. In some embodiments where the inlet flow face 1952defines a taper for at least a portion of the axial flow face lengthL_(inlet), the taper increases for at least a portion of the axial flowface length L_(inlet) from the first end 1912 towards the second end1914, such as in the example shown in FIG. 2, where the general shapedefined by the inlet flow face 1952 is a rounded cone. The taper of theinlet flow face 1952 can continuously change along the axial flow facelength L_(inlet) from the first end 1912 towards the second end 1914.Indeed, in the current example, the taper of the inlet flow face 1952continuously increases along the axial flow face length L_(inlet) fromthe first end 1912 towards the second end 1914.

A radial distance R_(1,2) is generally defined between the inlet flowface 1952 and the housing 1910 relative to the central axis z. Invarious embodiments, the radial distance R_(1,2) increases for at leasta portion of the axial flow face length L_(inlet) from the first end1912 towards the second end 1914 of the housing 1910, as demonstrated bya first radial distance R₁ and a second radial distance R₂. The firstradial distance R₁ is measured from a point on the inlet flow face 1952that is in axial alignment with the point on the inlet flow face 1952from which the second radial distance R₂ is measured, for purposes ofthis comparison. As such, the first radial distance R₁ and a secondradial distance R₂ are in parallel and in axial alignment. Increasingthe radial distance R_(1,2) along the axial flow face length L_(inlet)can help encourage spiraling airflow about the filter assembly 1950towards the second end 1914 of the housing 1910. Other configurations,however, are certainly contemplated.

In the current example, the housing 1910 maintains a relativelyconsistent distance from the central axis z. In some embodiments,however, the housing 1910 can define a taper. In such embodiments, thehousing 1910, and particularly the interior volume 1916 of the housing1910, can taper for at least a portion of the axial length from thefirst end 1912 to the second end 1914 or from the second end 1914 to thefirst end 1912. However, the radial distance between the inlet flow face1952 and the housing 1910 can increase along at least a portion of theaxial length of the inlet flow face 1952 from the first end 1912 to thesecond end 1914 of the housing 1910.

The annulus defined between the inlet flow face 1952 and the housing1910 in a cross-section perpendicular to the z-axis has an increasingarea along at least a portion of the axial length of the inlet flow face1952 from the first end 1912 to the second end 1914 of the housing 1910.FIGS. 25a and 25b depict simplified schematics of such examplecross-sections, where FIG. 25a is a cross-section at R₁ in FIG. 2, andFIG. 25b is a cross-section at R₂ in FIG. 2. While FIGS. 25a and 25bdepict the cross-sectional shape of the inlet flow face 1952 as having asmooth circular shape for simplicity, in various embodiments fluteprofiles will form the outer perimeter of the inlet flow face 1952. Forexample, a series of peaks and valleys that define the flute profiles inthe media are arranged about the central axis z to define a generallycircular shape.

The area of the annulus A₁ defined between the outer circumferentiallimit of the inlet flow face 1952 and the housing 1910 in FIG. 25a isless than the area of the annulus A₂, where A₁ is at a first position P₁along the axial length of the inlet flow face 1952 and A₂ is at a secondposition P₂ along the axial length of the inlet flow face 1952.“Annulus” is defined herein as a shape defined between an inner boundaryand an outer boundary, such as a ring, where the inner boundary and theouter boundary are not necessarily circles, are not necessarilyconcentric, and are not necessarily the same shape. FIGS. 25a and 25balso depict the radial distances R_(1,2) defined between the inlet flowface 1952 and the housing 1910 relative to the central axis z at thefirst position P₁ and the second position P₂ along the axial length ofthe inlet flow face 1952. The second radial distance R₂ is greater thanthe first radial distance R₁.

As mentioned above, in the current example, the general shape defined bythe inlet flow face 1952 forms a rounded, regular cone. By “regular” itis meant that the cone is generally symmetric about the z-axis. The coneis not necessarily perfectly symmetric about the z-axis. In some otherembodiments, the inlet flow face can have alternate configurations, someof which are described below with reference to other figures describedherein. For example, the general shape defined by the inlet flow facecan be irregular, in other words asymmetric about the z-axis. FIGS. 14A,26 a and 26 b discussed in detail below, provides one such example wherea flow face forms the general shape of a rounded, oblique cone.

In various embodiments, the filter assembly 1950 is positioned centrallyin the housing 1910 such that the z-axis extends centrally through thefilter assembly 1950. In the example currently depicted, the filtermedia 1956 is at least a first sheet of filter media and a second sheetof filter media in a coiled configuration about the z-axis, which willbe described in more detail with respect to FIG. 3, below. In some otherembodiments, the filter assembly is eccentric in the housing such thatthe z-axis does not extend centrally through the filter assembly. FIGS.27a and 27b depict cross sections perpendicular to the central axis zassociated with an example where a filter assembly 1950′ is positionedeccentrically in the housing 1910. The example filter assembly 1950′ canotherwise be consistent with the filter assembly of FIG. 2, except thatthe filter assembly 1950′ has a central axis Z extending axially throughthe filter assembly 1950′ distinct from the central axis z of thehousing 1910.

Similar to FIGS. 25a and 25b discussed above, the area of the annulus A₁defined between inlet flow face 1952′ and the housing 1910 in FIG. 27ais less than the area of the annulus A₂. A₁ is at a first position P₁along the axial length of the inlet flow face 1952′ and A₂ is at asecond position P₂ along the axial length of the inlet flow face 1952′.Furthermore, the radial distances R_(1,2) defined between the inlet flowface 1952′ and the housing 1910 relative to the central axis z at thefirst position P₁ and the second position P₂ along the axial length ofthe inlet flow face 1952′ are different. The second radial distance R₂is greater than the first radial distance R₁, where the first radialdistance R₁ and the second radial distance R₂ are in axial alignment andin parallel.

Returning to the example of FIGS. 1-2, the filter assembly 1950 has arod 1990 that the filter media 1956 is coiled about. As such, the rod1990 extends centrally through at least a portion of the filter assembly1950. In some embodiments the rod 1990 extends entirely through thefilter assembly 1950. The rod 1990 is a single component, or can beconstructed of multiple components that are coupled or uncoupled to eachother. In some embodiments the rod 1990 does not extend entirely throughthe filter assembly 1950, while in other embodiments, the rod 1990 doesextend entirely through the filter assembly 1950. In one example the rod1990 has a tubular extension with plugs disposed in each end of thetubular extension. In such an embodiment a plug can form a handle, whichis described in more detail below.

A rod receptacle 1992 defined by the second end 1914 of the housing 1910is configured to receive a distal end 1994 of the rod 1990. The rod 1990can have a proximal end positioned towards the outlet flow face 1954(not currently visible). In some embodiments a proximal end of the rod1990 is positioned between the inlet flow face 1952 and the outlet flowface 1954. The distal end of the rod 1990 is positioned towards theinlet flow face 1952. In such an embodiment the rod receptacle 1992 is apositioning feature that helps maintain positioning of the inlet flowface 1952 of the filter assembly 1950 relative to the second end 1914 ofthe housing 1910. Particularly here, the rod receptacle 1992 is acentering feature that helps maintain centering of the inlet flow face1952 filter assembly 1950 relative to the second end 1914 of the housing1910. In some embodiments, the distal end 1994 of the rod 1990 defines ahandle that can be manually grasped by a user which can aid in removaland installation of the filter assembly 1950 relative to the housing1910.

In various embodiments, a rod can be omitted from the system. In someother embodiments, rather than defining a rod receptacle as depicted inFIG. 2, the second end of the housing can define a rod structureextending axially towards the first end of the housing. The inlet flowface of the filter assembly can be configured to receive the rodstructure for positioning the inlet flow face of the filter assemblyrelative to the second end of the housing. For example, a rod receptaclecan be coupled to the inlet flow face of the filter assembly. In somesuch embodiments the rod receptacle can define a handle structure thatcan be grasped by a user, such as one or more radial projectionsextending from the rod receptacle. Other features can also beimplemented to secure the position of the inlet flow face of the filterassembly relative to the second end of the housing.

In some embodiments, the housing 1910 can have a positioning featurethat directly receives the distal end of the inlet flow face 1952. Forexample, the second end 1914 of the housing 1910 can define an annularprotrusion extending circumferentially about the central axis of thefilter assembly 1950. The annular protrusion can be configured tosurround the distal end of the inlet flow face 1952. In someembodiments, the annular protrusion can be configured to frictionallyengages the distal end of the inlet flow face 1952. In variousembodiments an annular protrusion as a positioning feature is omittedfrom the separator system 1900.

FIG. 3 depicts an example filter assembly consistent with the systemsdepicted in FIGS. 1-2. The filter assembly 1 is constructed of filtermedia 10 defining a first flow face 20, a second flow face 30, and aplurality of flutes 40 extending from the first flow face 20 to thesecond flow face 30 in an axial direction. In the current example, thefirst flow face is defined on a first end 12 of the filter assembly 1and the second flow face 30 is defined on a second, opposite end 14 ofthe filter assembly 1. The first end 12 and the second end 14 areopposite axial ends of the filter assembly 1. Consistent with FIG. 2,above, the first flow face 20 can be the inlet flow face and the secondflow face 30 can be the outlet flow face. The first flow face 20 definesan axial flow face length L, as described above. The first flow face 20defines a taper for at least a portion of the axial flow face length, asdescribed above.

The filter media 10 is a plurality of sheets of filter media,specifically a first sheet of filter media 50 and a second sheet offilter media 60. The second sheet of filter media 60 is adjacent to thefirst sheet of filter media 50. The first sheet of filter media 50 andthe second sheet of filter media 60 mutually define the plurality offlutes 40. The filter media 10 defines a coiled configuration about aZ-axis. Accordingly, each of the first sheet of filter media 50 and thesecond sheet of filter media 60 defines a coiled configuration aroundthe Z-axis. As such, the plurality of flutes 40 are also in a coiledconfiguration about the Z-axis.

The first sheet of filter media 50 and the second sheet of filter media60 are generally elongate, which enables the first sheet of filter media50 and the second sheet of filter media 60 to be coiled about theZ-axis, which extends in the axial direction, to form a filter assembly.In this example, the first sheet of filter media 50 and the second sheetof filter media 60 are continuous, meaning that the first sheet offilter media 50 and the second sheet of filter media 60 are portions ofa single cohesive sheet of filter media. The first sheet of filter media50 and the second sheet of filter media 60 are separated by a fold 70.The fold 70 defines the second flow face 30 of the filter assembly. Thefirst sheet of filter media 50 defines a first edge 52 and the secondsheet of filter media 60 defines a second edge 62. The first edge 52 andthe second edge 62 mutually define the first flow face 20 of the filterassembly 1. An “edge” of a media sheet is defined herein as the outerlimit of the media sheet and is distinguished from the fold 70.

In some alternate embodiments, which will be described in more detailbelow, the first sheet of filter media 50 and the second sheet of filtermedia 60 are separate sheets, in which case, the second flow face wouldbe defined by the edges of each of the sheets of filter media. Further,in various embodiments, the first sheet of filter media can benon-fluted and characterized as a facing sheet of filter media abuttingthe fluted second sheet of filter media to form single facer media.

In examples consistent with the current embodiment, both the first sheetof filter media 50 and the second sheet of filter media 60 are eachfluted. The term “fluted” as used herein is synonymous with the term“corrugated,” which refers to a series of alternating elongateridges/peaks, and elongate grooves/valleys. The term “flutes” is usedherein to refer to the elongate channels mutually defined by adjacentportions of media. In the current embodiment the plurality of flutes areparallel, but in some other embodiments the plurality of flutes are notparallel.

The filter assembly 1 is generally constructed to define a fluid pathway16 between the first flow face 20 and the second flow face 30 throughthe filter media 10 such that the fluid is filtered by the filter media10. In particular, the plurality of flutes 40 defines the fluid pathway16 either (1) into the filter assembly 1 then to the filter media(“inlet flutes”), or (2) from the filter media 10 out of the filterassembly 1 (“outlet flutes”). While each of the figures provided in thepresent application depict fluid pathways in a particular directionthrough the depicted filter assemblies for clarity, it will beunderstood that the fluid pathways can also be in the reverse directionin various examples.

Each of the plurality of flutes 40 defines a flute opening 42 and aflute closure 70. The flute opening 42 forms an end-most portion of thefluid pathway 16 along the flute, to accommodate fluid flow into or outof the filter assembly 1. The flute closure 70 obstructs fluid flowalong the flute, thereby defining a portion of the fluid pathway 16through the filter media 10. In the current example, a plurality ofinlet flutes defines the flute opening 42 at the first flow face 20. Aflute closure 70 can be defined towards the second flow face 30 in someembodiments. In some embodiments, including the one depicted, the fluteclosure 70 is adjacent to the second flow face 30. More particularly,the flute closure 70 can abut the second flow face 30. The flute closure70 can have a variety of different configurations, but in the currentembodiment, the flute closure 70 is defined by the fold 70, whichdefines the second flow face 30. In some other embodiments, fluteclosures can be defined between the first flow face 20 and the secondflow face.

In the current embodiment, the volume defined between an outer surface56 of the first sheet of filter media and the outer surface 66 of thesecond sheet of filter media defines an outlet pathway of the fluidpathway 16 that is not necessarily characterized as being defined by aplurality of flutes. The phrase “outer surface” is defined as thesurfaces of the first sheet of filter media and the second sheet offilter media that are facing away from each other if the filter media 10were arranged as a flat sheet (when uncoiled. The outlet pathway extendsfrom an obstruction 72 to an opening defined at the second end 14 of thefilter assembly 1 between the coiled fold 70.

The obstruction 72 can be disposed within the coil and outside of theplurality of flutes 40 such that fluids passing through the first flowface 20 and second flow face 30 of the filter assembly 1 must first passthrough the filter media 10. Additional obstructions can also bedisposed in any other gaps in the filter media to prevent fluid flowthere-through, such as around the outer perimeter of the filter assembly1 and in a central opening of the filter assembly 1. An obstruction canbe formed through depositing an adhesive, such as a glue bead at therelevant location.

Each of the plurality of flutes 40 defines a flute distance between thefirst flow face 20 and the second flow face 30. The “flute distance” asdefined herein is the distance between a first end of a particular fluteat the first flow face of the filter assembly and the second end of theparticular flute at the second flow face of the filter assembly. In thecurrent embodiment each of the plurality of flutes 40 are straight and,as such, the length of the flute is equal to the “flute distance” asdefined herein. However, in some alternative embodiments, the “flutedistance” is unequal to the length of the flute, such as in embodimentswhere the flutes are curved or otherwise do not form a single straightline. Furthermore, the “flute distance” is defined to be the maximumdistance between the ends of the flute, in embodiments where the ends ofthe flute are not a consistent distance apart.

In the current embodiment, a first flute 44 of the plurality of flutes40 defines a first flute distance D₁ between the first flow face 20 andthe second flow face 30 and a second flute 46 of the plurality of flutes40 defines a second flute distance D₂ between the first flow face 20 andthe second flow face 30. In some examples, the first flute distance D₁is less than the second flute distance D₂, as currently depicted. Insome other examples, the first flute distance D₁ is greater than thesecond flute distance D₂. In certain embodiments, the first flutedistance D₁ and the second flute distance D₂ differ by greater than 2mm. In some embodiments, the first flute distance D₁ differs from thesecond flute distance D₂ by at least 5 mm, at least 8 mm or even atleast 15 mm. In some embodiments, the first flute distance D₁ differsfrom the second flute distance D₂ by 3 mm to 20 mm, 10 mm to 20 mm, or15 mm to 25 mm.

In some embodiments, a third flute 48 of the plurality of flutes 40defines a third flute distance D₁ between the first flow face 20 and thesecond flow face 30. The third flute distance D₁ will generally differfrom at least one of the first flute distance D₁ and the second flutedistance D₂ by greater than 2 mm. In some embodiments the third flutedistance D₁ differs from both the first flute distance D₁ and the secondflute distance D₂ by greater than 2 mm. The third flute distance D₁ candiffer from one or both the first flute distance D₁ and the second flutedistance D₂ by similar ranges described above. In the current example,the third flute distance D₁ is greater than the first flute distance D₁and the second flute distance D₂. In some other examples, the thirdflute distance D₁ is greater than one of the first flute distance D₁ andthe second flute distance D₂, and less than the other of the first flutedistance D₁ and the second flute distance D₂, as will be appreciated.

The differences in flute distances between the first flow face 20 of thefilter assembly 1 and the second flow face 30 of the filter assembly 1is also evidenced by the shapes of the flow faces relative to eachother. In various embodiments, at least one of the first flow face 20and the second flow face 30 is non-planar. In various embodiments, atleast one of the first flow face 20 and the second flow face 30 issubstantially planar. A “planar” flow face as defined herein means thatthe surface(s) of the media defining the flow face form an imaginaryplane within a 2 mm margin of error.

In some examples consistent with this particular embodiment, the firstflow face 20 is non-planar and the second flow face 30 is planar. Insome other examples consistent with this particular embodiment, thefirst flow face 20 is non-planar and the second flow face 30 non-planar.Here the first flow face 20 defines a spiral about the Z-axis thatextends in the axial direction. While the second flow face 30 isobstructed from view in the current illustration, it will be appreciatedthat the second flow face 30 can be non-planar or planar. For example,in some embodiments the second flow face 30 can be recessed and extendinward relative to the filter assembly, similar to the flow facesdepicted in FIG. 18.

It will be appreciated that, in some alternative embodiments, the firstflow face 20 can be planar and the second flow face 30 can benon-planar. In some embodiments at least one flute in the plurality offlutes 40 defines a flute opening that is non-planar, where “non-planar”means that the flute opening does not define a plane within a 2 mmmargin of error.

In examples consistent with the current embodiment, the obstruction 72is disposed adjacent to the second edge 62 of the second sheet of filtermedia 60 along the length of the second sheet of filter media 60. As thesecond edge 62 of the second sheet of filter media 60 is non-planar, theobstruction 72 also is non-planar. In some embodiments where a filterface is non-planar, an obstruction disposed adjacent to the filter faceis also non-planar. However, in other embodiments, where a filter faceis non-planar, an obstruction disposed adjacent to that filter face isplanar, such as in the embodiment depicted in FIG. 4A.

FIG. 4A depicts another example filter assembly 100 consistent with thetechnology disclosed herein. The filter assembly 100 is constructed offilter media 110 defining a first flow face 120, a second flow face 130,and a plurality of flutes 140 extending from the first flow face 120 tothe second flow face 130. In the current example, the first flow face120 is defined on a first end 102 of the filter assembly 100 and thesecond flow face 130 is defined on a second, opposite end 104 of thefilter assembly 100. The first flow face 120 defines a first axial flowface length L₁ and the second flow face 130 defines a second axial flowface length L₂. In the current example, the first flow face 120 does notdefine a taper.

The filter media 110 is a plurality of sheets of filter media,specifically a first sheet of filter media 150 and a second sheet offilter media 160. The second sheet of filter media 160 is adjacent tothe first sheet of filter media 150. The first sheet of filter media 150and the second sheet of filter media 160 mutually define the pluralityof flutes 140. The filter media 110 defines a coiled configuration abouta Z-axis. Accordingly, each of the first sheet of filter media 150 andthe second sheet of filter media 160 defines a coiled configurationabout the Z-axis. As such, the plurality of flutes 140 are also in acoiled configuration about the Z-axis. To depict components nototherwise visible, an end portion 101 of the filter media 110 isdepicted in a cut-away view that extends outward from the coil, butgenerally the substantial length of the filter media 110 is in a coiledconfiguration. In this example, the plurality of flutes 140 aregenerally parallel.

The first sheet of filter media 150 and the second sheet of filter media160 are generally elongate. In this example, the first sheet of filtermedia 150 and the second sheet of filter media 160 are discontinuous,meaning that the first sheet of filter media 150 and the second sheet offilter media 160 are separate sheets of filter media. In examplesconsistent with the current embodiment, the first sheet of filter media150 is a fluted sheet and the second sheet of filter media 160 is afacing sheet, where a “facing sheet” is generally defined as a planar,unfluted sheet.

The first sheet of filter media 150 defines a first edge 152 and asecond edge 154 that is opposite the first edge 152. The first edge 152defines the first flow face 120 and the second edge 154 defines thesecond flow face 130. The first sheet of filter media 150 has a firstwidth W₁ that is defined by the perpendicular distance from first edge152—or first flow face 120—to the second edge 154—or second flow face130, where the first width W₁ is substantially constant along the lengthof the first sheet of filter media 150. Similarly, the second sheet offilter media 160 defines a third edge 162 and a fourth edge 164 that isopposite the third edge 162. The third edge 162 defines the first flowface 120 and the fourth edge 164 defines the second flow face 130. Thesecond sheet of filter media 160 has a second width W₂ that is definedby the perpendicular distance from the third edge 162—or the first flowface 120—to the fourth edge 164—or the second flow face 130, where thewidth is substantially constant along the length of the second sheet offilter media 160. In the current embodiment, the first width W₁ differsfrom the second width W₂ by greater than 2 mm.

The filter assembly 100 is generally constructed to define a fluidpathway 116 between the first flow face 120 and the second flow face 130through the filter media 110 such that the fluid is filtered by thefilter media 110. Each of the plurality of flutes 140 defines a fluteopening 142, which is more clearly visible in FIG. 4b as a detail viewof FIG. 4a . Each of the plurality of flutes 140 defines a flute closure170, which is visible in FIG. 4a because a portion of the first sheet offilter media 150 is cut away for clarity. In the current example, theflute opening 142 is defined at the first flow face 120 and the fluteclosure 170 is defined towards the second flow face 130. In someembodiments, including the one depicted, the flute closure 170 isadjacent to the second flow face 130. More particularly, the fluteclosure 170 can abut the second flow face 130. The flute closure 170 canhave a variety of different configurations, but in the currentembodiment, the flute closure 170 is a physical barrier such as a gluebead disposed between the first sheet of filter media 150 and the secondsheet of filter media 160 towards the second flow face.

An obstruction 172 can be disposed within the coil and outside of theplurality of flutes 140 such that fluids passing through the first flowface 120 and second flow face 130 of the filter assembly 100 must firstpass through the filter media 110. Additional obstructions can also bedisposed in any other gaps in the filter media to prevent fluid flowtherethrough, such as around the outer perimeter of the filter assembly100 and in a central opening of the filter assembly 100. An obstructioncan be formed through depositing an adhesive, such as a glue bead orother barrier at the relevant location.

In various embodiments, including the one depicted, at least one of thefirst flow face 120 and the second flow face 130 is non-planar. Inexamples consistent with this particular embodiment, the first flow face120 is non-planar and the second flow face 130 is non-planar. Inparticular, the first edge 152 and the third edge 162 (particularlyvisible in FIG. 4b ) that define the first flow face 120 are non-planar,even though the first edge 152 is planar and the third edge 162 isplanar. The second edge 154 and fourth edge 164 that define the secondflow face 130 are similarly non-planar, even though the second edge 154is planar and the fourth edge 164 is planar. In the current embodimentthe flute closure 170 is disposed adjacent to the fourth edge 164 of thesecond sheet of filter media 160 and, as such, the flute closure 170 isgenerally planar, but in some alternate examples the flute closure 170is non planar. Similarly, the obstruction 172 is disposed adjacent tothe third edge 162 of the second sheet of filter media 160 and so theobstruction 172 is also planar, but in some alternate examples theobstruction 172 is non-planar.

In various embodiments, at least one flute of the plurality of flutesdefines an opening that is non-planar, such as a first flute 144 (FIG.4b ) in this example embodiment. In particular, in the currentembodiment all of the plurality of flutes 140 define a non-planaropening, by virtue of the first edge 152 and third edge 162 defining oneflute opening and the second edge 154 and fourth edge 164 defining theother flute opening.

FIG. 5 depicts a side cut-away view of yet another example filterassembly 200 consistent with the technology disclosed herein. The filterassembly 200 is constructed of filter media 210 having a first elongateedge 212 defining a first flow face 220, a second elongate edge 214defining a second flow face 230, and a plurality of flutes 240 extendingfrom the first flow face 220 to the second flow face 230. In the currentexample, the first flow face 220 is defined on a first end 202 of thefilter assembly 200 and the second flow face 230 is defined on a second,opposite end 204 of the filter assembly 200. The first flow face 220 hasan axial flow face length L. The first flow face 220 also defines ataper for at least a portion of the axial flow face length from thefirst end 202 towards the second end 204. In the current example, thetaper is relatively constant for at least a portion of the axial flowface length from the first end 202 towards the second end 204.

Similar to the embodiments depicted in FIGS. 3-4 b, the filter assembly200 is generally constructed to define a fluid pathway 218 between thefirst flow face 220 and the second flow face 230 through the filtermedia 210 such that the fluid is filtered by the filter media 210. Assuch, in this example, each of the plurality of flutes 240 defines aflute opening and a flute closure. Also similar to the embodimentsdepicted in FIGS. 3-4 b, the filter assembly 200 is constructed offilter media 210 that is in a coiled configuration about a Z-axis.Example filter media 210 configurations consistent with FIG. 5 and otherembodiments disclosed herein will be described in more detail below withreference to FIGS. 6a -6 d.

Returning to FIG. 5, each of the plurality of flutes 240 defines a flutedistance between the first flow face 220 and the second flow face 230.In the current embodiment, a first flute 244 of the plurality of flutes240 defines a first flute distance D₁ between the first flow face 220and the second flow face 230 and a second flute 246 of the plurality offlutes 240 defines a second flute distance D₂ between the first flowface 220 and the second flow face 230. In the current embodiment thefirst flute distance D₁ is less than the second flute distance D₂, butin other embodiments the first flute distance D₁ is greater than thesecond flute distance D₂. In a variety of embodiments, the first flutedistance D₁ and the second flute distance D₂ differ by greater than 2mm. In some embodiments, the first flute distance D₁ differs from thesecond flute distance D₂ by at least 5 mm, at least 8 mm or even atleast 15 mm. In some embodiments, the first flute distance D₁ differsfrom the second flute distance D₂ by 3 mm to 20 mm, 10 mm to 20 mm, or15 mm to 25 mm.

In some embodiments, a third flute 248 of the plurality of flutes 240defines a third flute distance D₁ between the first flow face 220 andthe second flow face 230. In the current embodiment the third flutedistance D₁ is greater than the first flute distance D₁ and the secondflute distance D₂, but flute distances can have other relativerelationships, as has been described above. The third flute distance D₁will generally differ from at least one of the first flute distance D₁and the second flute distance D₂ by greater than 2 mm. In someembodiments the third flute distance D₁ differs from both the firstflute distance D₁ and the second flute distance D₂ by greater than 2 mm.The third flute distance D₁ can differ from one or both the first flutedistance D₁ and the second flute distance D₂ by similar ranges describedabove.

In various embodiments, at least one of the first flow face 220 and thesecond flow face 230 is planar. In examples consistent with thisparticular embodiment, the first flow face 220 is planar and the secondflow face 230 is planar, and the first flow face 220 is non-parallel tothe second flow face 230. In some embodiments one or both of the firstflow face and the second flow face can be non-planar. For example, oneor both of the first flow face and the second flow face can be cut to bea three-dimensional surface.

The filter assembly 200 of FIG. 5 can be constructed from variety ofconfigurations of filter media 210, examples of which are depicted anddescribed in association with FIGS. 6a-6d and also described in generallater in this document. Referring first to FIG. 6a , the example filtermedia 210 is a plurality of sheets of filter media, specifically a firstsheet of filter media 250 and a second sheet of filter media 260. Thesecond sheet of filter media 260 is adjacent to the first sheet offilter media 250. The first sheet of filter media 250 and the secondsheet of filter media 260 mutually define the plurality of flutes 240.While currently depicted in an uncoiled arrangement, to be consistentwith FIG. 5, the filter media 210 is arranged in a coiled configurationabout a Z-axis (FIG. 5). Accordingly, each of the first sheet of filtermedia 250 and the second sheet of filter media 260 are arranged todefine a coiled configuration about the Z-axis. As such, the pluralityof flutes 240 are also in a coiled configuration about the Z-axis. Inthis example, the plurality of flutes 240 are generally parallel. Inexamples consistent with the embodiment of FIG. 6a , the first sheet offilter media 250 is a fluted sheet and the second sheet of filter media260 is a fluted sheet.

The first sheet of filter media 250 and the second sheet of filter media260 are generally elongate. In this example, the first sheet of filtermedia 250 and the second sheet of filter media 260 are continuous andseparated by a fold 270. The fold 270 defines the second flow face 230and the second elongate edge 214 of the filter assembly 200 depicted inFIG. 5. The first sheet of filter media 250 defines a first edge 252 andthe second sheet of filter media 260 defines a second edge 262. Thefirst edge 252 and the second edge 262 are configured to mutually definethe first flow face 220, and therefore the first elongate edge 212, ofthe filter assembly 200 (FIG. 3).

In the current example filter media 210, flute openings 242 (visible inFIG. 6a ) of the plurality of flutes 240 is defined at the first flowface 220 (visible in FIG. 5) and a flute closure 270 (visible in FIG. 6a) is defined towards the second flow face 230 (visible in FIG. 5). Insome embodiments, including the one depicted, the flute closure 270 isadjacent to the second flow face 230 (FIG. 5). More particularly, theflute closure 270 can abut the second flow face 230. The flute closure270 can have a variety of different configurations, but in theembodiment of FIG. 6a , the flute closure 270 is the fold 270 betweenthe first sheet of filter media 250 and the second sheet of filter media260.

An obstruction 272 can be disposed outside of the plurality of flutes240 such that fluids passing through the first flow face 220 and secondflow face 230 of the filter assembly 200 (FIG. 5) must first passthrough the filter media 210. The obstruction can be disposed towardsthe first elongate edge 212 of the filter media 210 during constructionof the filter assembly 200 of FIG. 5. As has been described, additionalobstructions can also be disposed in any other gaps in the filter media210 to prevent fluid flow therethrough, such as around the outerperimeter of the filter assembly 200 and in a central opening of thefilter assembly 200. An obstruction can be formed through depositing anadhesive, such as a glue bead at the relevant location.

As has been mentioned, to construct the filter assembly 200 of FIG. 5,the filter media 210 of FIG. 6a is coiled around a Z-axis, andobstructions 272 are disposed in contact with the filter media 210 atrelevant locations to elicit the desired fluid flow through the media.In various embodiments, after the filter media 210 is coiled into acylindrical shape, the filter media 210 is cut to form the desired shapeof the first flow face 220. In the embodiment depicted in FIG. 5, thefirst flow face 220 can be cut with a cutting tool to form a plane thatis non-parallel to the second flow face 230. In examples consistent withthe current embodiment the second flow face 230 is generally not cut dueto the presence of the fold 270, which forms an obstruction that guidesfluid flow. The filter media 210 can be cut using laser cutting, in someexamples, and in other examples the filter media 210 can be cut using asharp edge, such as a saw or knife blade. In such embodiments, theobstructions 272 can be disposed in contact with the filter media 210 atlocations that will not be cut and removed.

In some alternative embodiments, the first elongate edge 212 of thefilter media 210 is cut before being coiled to form the intended shapeof the relevant flow face(s) after the filter media 210 is coiled.

FIG. 6b depicts another filter media 210 consistent with the embodimentdepicted in FIG. 5 before the filter media is coiled and cut. The filtermedia 210 is a plurality of sheets of filter media, specifically a firstsheet of filter media 257 and a second sheet of filter media 267. Thesecond sheet of filter media 267 is adjacent to the first sheet offilter media 257. The first sheet of filter media 257 and the secondsheet of filter media 267 mutually define the plurality of flutes 240depicted in FIG. 5.

The first sheet of filter media 257 and the second sheet of filter media267 are generally elongate. In this example, the first sheet of filtermedia 257 and the second sheet of filter media 267 are discontinuous.The first sheet of filter media 257 defines a first edge 254 and thesecond sheet of filter media 267 defines a second edge 264. The firstedge 254 and the second edge 264 are configured to mutually define thefirst flow face 220, and therefore the first elongate edge 212, of thefilter assembly 200 (FIG. 5). The first sheet of filter media 257defines a third edge 256 and the second sheet of filter media 267defines a fourth edge 266. The third edge 256 and the fourth edge 266are configured to mutually define the second flow face 230, andtherefore the second elongate edge 214, of the filter assembly 200 (FIG.3).

For construction of the filter assembly 200 of FIG. 5, the filter media210 is arranged in a coiled configuration about a Z-axis (FIG. 5).Accordingly, each of the first sheet of filter media 257 and the secondsheet of filter media 267 are arranged to define a coiled configurationabout the Z-axis. As such, the plurality of flutes 240 are also in acoiled configuration about the Z-axis. In this example, the plurality offlutes 240 are generally parallel. In examples consistent with theembodiment of FIG. 6b , the first sheet of filter media 257 is a flutedsheet and the second sheet of filter media 267 is also a fluted sheet.

In the current example filter media 210, the flute opening 245 (visiblein FIG. 6b ) is defined at the first flow face 220 (visible in FIG. 5)and a flute closure 275 (visible in FIG. 6b in a tear-away section) isdefined towards the second flow face 230 (visible in FIG. 5). In someembodiments, including the one depicted in FIG. 6b , the flute closure275 is adjacent to the second flow face 230 (FIG. 5). More particularly,the flute closure 275 can abut the second flow face 230. The fluteclosure 275 can have a variety of different configurations, but in theembodiment of FIG. 6b , the flute closure 275 is a physical obstruction,such as a glue bead deposited between the first sheet of filter media257 and the second sheet of filter media 267.

An obstruction 273 can be disposed outside of the plurality of flutes240 such that fluids passing through the first flow face 220 and secondflow face 230 of the filter assembly 200 (FIG. 5) must first passthrough the filter media 210. The obstruction can be disposed towardsthe first elongate edge 212 of the filter media 210 during constructionof the filter assembly 200 of FIG. 5. As has been described, additionalobstructions can also be disposed in any other gaps in the filter media210 to prevent fluid flow therethrough, such as around the outerperimeter of the filter assembly 200 and in a central opening of thefilter assembly 200.

The filter media 210 of FIG. 6b can be cut and formed into a filterassembly 200 similarly to the filter media described in FIG. 6a , above.

FIG. 6C depicts yet another filter media 210 consistent with theembodiment depicted in FIG. 5 before the filter media is coiled and cut.The filter media 210 is a plurality of sheets of filter media,specifically a first sheet of filter media 251 and a second sheet offilter media 261. The second sheet of filter media 261 is adjacent tothe first sheet of filter media 251. The first sheet of filter media 251and the second sheet of filter media 261 mutually define the pluralityof flutes 240.

The first sheet of filter media 251 and the second sheet of filter media261 are generally elongate. In this example, the first sheet of filtermedia 251 and the second sheet of filter media 261 are discontinuous.The first sheet of filter media 251 defines a first edge 253 and thesecond sheet of filter media 261 defines a second edge 263. The firstedge 253 and the second edge 263 are configured to mutually define thefirst flow face 220, and therefore the first elongate edge 212, of thefilter assembly 200 (FIG. 5). The first sheet of filter media 251defines a third edge 255 and the second sheet of filter media 261defines a fourth edge 265. The third edge 255 and the fourth edge 265are configured to mutually define the second flow face 230, andtherefore the second elongate edge 214, of the filter assembly 200 (FIG.5).

For construction of the filter assembly 200 of FIG. 5, the filter media210 is arranged in a coiled configuration about a Z-axis (FIG. 5).Accordingly, each of the first sheet of filter media 251 and the secondsheet of filter media 261 are arranged to define a coiled configurationabout the Z-axis. As such, the plurality of flutes 240 are also in acoiled configuration about the Z-axis. In this example, the plurality offlutes 240 are generally parallel. In examples consistent with theembodiment of FIG. 6c , the first sheet of filter media 251 is a flutedsheet and the second sheet of filter media 261 is a facing sheet.

In the current example filter media 210, the flute opening 243 (visiblein FIG. 6c ) is defined at the first flow face 220 (visible in FIG. 5),and a flute closure 271 (visible in FIG. 6b in a tear-away section) isdefined towards the second flow face 230 (visible in FIG. 5). In someembodiments, including the one depicted in FIG. 6c , the flute closure271 is adjacent to the second flow face 230 (FIG. 5). More particularly,the flute closure 271 can abut the second flow face 230. The fluteclosure 271 can have a variety of different configurations, but in theembodiment of FIG. 6c , the flute closure 271 is a physical obstruction,such as a glue bead deposited between the first sheet of filter media251 and the second sheet of filter media 261.

An obstruction 273 can be disposed outside of the plurality of flutes240 such that fluids passing through the first flow face 220 and secondflow face 230 of the filter assembly 200 (FIG. 5) must first passthrough the filter media 210. The obstruction can be disposed towardsthe first elongate edge 212 of the filter media 210 during constructionof the filter assembly 200 of FIG. 5. As has been described, additionalobstructions can also be disposed in any other gaps in the filter media210 to prevent fluid flow therethrough, such as around the outerperimeter of the filter assembly 200 and in a central opening of thefilter assembly 200.

The filter media 210 of FIG. 6c can be cut and formed into a filterassembly 200 similarly to the filter media described in FIG. 6a , above.

FIG. 6d is a facing view of a relatively larger elongate segment of thefilter media 210 than those depicted in FIGS. 4a-4c to convey anunderstanding of the general overall shape of the filter media 210 in anuncoiled configuration. FIG. 6d can generally be consistent with themedias depicted in each of FIGS. 6a-6c . FIG. 6d shows that the filtermedia 210 has a first elongate edge 280, a second elongate edge 282, afirst terminal edge 284, and a second terminal edge 286. The firstelongate edge 280 corresponds to the first edge of the first sheet offilter media and the second edge of the second sheet of filter media inFIGS. 6a-6c , described above. As such, the first elongate edge 280 alsodefines the first flow face 220 of the filter assembly (FIG. 5). Thesecond elongate edge 282 can correspond to the fold 270 between thefirst sheet of filter media and the second sheet of filter media in FIG.6a , or the third edge of the first sheet of filter media and the fourthedge of the second sheet of filter media of FIGS. 6b -6 c.

The first elongate edge 280 generally forms a sine wave pattern havingan increasing or decreasing frequency across the length of the filtermedia 210. The second elongate edge 282 extends in a generally straightline. Similarly, the first terminal edge 284 and the second terminaledge 286 extend in straight lines, and each are perpendicular to thesecond elongate edge 282. In the current example, the filter media 210does not form a trapezoidal shape at least due to the wave pattern ofthe first elongate edge 280.

Experimental Data

Example configurations generally consistent with the technologydisclosed herein were tested in example separator systems and comparedto a standard two-stage separator system that is consistent withprevious technologies. A cross-sectional view of the standard two-stageseparator 2100 is depicted in FIG. 29. The separator 2100 incorporates apleated, tubular filter media 2156 having an inlet that is formed by anouter cylindrical boundary 2152 of the filter assembly and an outlet2154 defined within a central opening 2158 of the tubular filter media.Retaining elements 2126 on each end of the separator housing 2110sealably receive the first end 2151 and second end 2153 of the filterassembly 2150 to direct airflow through the filter media 2156.

Three new designs generally consistent with the present technology weretested against the standard design. The filter assemblies and theseparator housings tested were sized similarly. The three filterassemblies consistent with the current disclosure were not tubularfilter elements having a radial inlet like in the standard design.Rather, each of the new filter elements were axial flow filters havingan inlet flow face having an axial length (as disclosed herein) and someinternal seals and support structures for the standard design were notneeded for the new designs. Each of the tested filter assembliesconsistent with the current disclosure were constructed of filter mediahaving a single-facer media structure, such as depicted and describedwith reference to FIG. 6C, above, that was coiled about a central axis.

A first new design (referenced as “New No. 1” in the Table, below) was afilter assembly generally consistent with that described with referenceto FIG. 2. The filter assembly was installed in a separator housingconsistent with that shown and described with reference to FIG. 29,above, where retaining elements were on each end of the separatorhousing that received the first end and second end (the inlet flow face)of the filter assembly. There was no seal between the retaining elementand the inlet flow face of the filter assembly, however. For the seconddesign (referenced as “New No. 2” in the Table, below), the filterassembly was the same as in the first design, but the retaining elementon the second end of the separator housing (which received the inletflow face of the filter assembly in the first new design and the secondend of the filter element in the standard design) was removed from theseparator housing.

A third new design (referenced as “New No. 3” in the Table, below) was afilter assembly generally consistent with that described with referenceto FIG. 2. The filter assembly 2250 was installed in a separator housing2210 generally consistent with that shown in FIG. 28. Retaining elementsconsistent with those discussed above with reference to FIG. 29 wereomitted. However, the housing 2210 has a centering feature 2290extending axially from the second end 2214 of the housing 2210 towardsthe first end 2212 of the housing 2210. The centering feature 2290engages the distal end of the inlet flow face 2252 to maintainpositioning of the distal end of the inlet flow face 2252. Furthermore,the access cover 2270 of the housing 2210 tapered inward towards thecentral axis z. The inlet and outlet of the separator housing 2210 wereenlarged compared to the other tested systems.

The initial pressure drop (dP), the dust on the element after testing(“element gain”), the total dust fed into the system, and the separationefficiency was measured. The air flow rate for each of the tests was setat 4.94 cubic meters per minute. Table 1, below reflects the results:

TABLE 1 dP Element Dust Separation Design (in-H₂O) Gain (g) Fed (g)Efficiency Standard 7.81 421.1 2851 85.52% New No. 1 9.22 280 258989.12% New No. 2 9.27 233 2753 91.45% New No. 3 7.08 472 3589 86.85%

The data reflects that, while the New Designs No. 1 and No. 2 had ahigher initial pressure drop than the Standard Design, there was anincrease in the separation efficiency of the system, which cancontribute to a longer filter life. New Design No. 3 had a lower initialpressure drop, but a higher separation efficiency than the StandardDesign. New Design No. 3 had a 12% increase in dust on the elementcompared to the Standard Design, and a 26% increase in the total dustfed into the system relative to the test of the Standard Design.

FIG. 7 depicts another example filter assembly 300 consistent with thetechnology disclosed herein. The filter assembly 300 is a panel filterassembly. The filter assembly 300 is constructed of filter media 310defining a first flow face 320, a second flow face 330, and a pluralityof flutes 340 extending from the first flow face 320 to the second flowface 330. In the current example of FIG. 7, the first flow face 320 isdefined on a first end 302 of the filter assembly 300 and the secondflow face 330 is defined on a second, opposite end 304 of the filterassembly 300. In the current example of FIG. 7, the first flow face 320is non-planar and the second flow face 330 is substantially planar, butin some other embodiments, each of the first flow face 320 and thesecond flow face 330 can be non-planar. The first flow face 320 has aflow face length L in the Z-direction. In the current example, the firstflow face 320 does not define a taper for at least a portion of theaxial flow face length from the first end towards the second end.

The filter media 310 is a plurality of sheets of filter media. Inparticular, the plurality of sheets of filter media has alternatingfluted sheets 352 of filter media and alternating facing sheets 354 offilter media. The plurality of sheets of filter media are in a stackedconfiguration. Each of the plurality of sheets of filter media arediscontinuous. Each sheet of filter media has a first edge 312 definingthe first flow face 320 of the filter assembly 300. In the currentembodiment, each sheet of filter media has a second edge 314 definingthe second flow face 330 of the filter assembly 300. The plurality ofsheets of filter media cumulatively define the plurality of flutes 340.Each of the plurality of flutes 340 defines a flute opening 342 and aflute closure 370, where an example flute closure 370 is visible where aportion of a facing sheet 354 is torn away from a fluted sheet 352. Eachof the plurality of flutes 340 defines a flute distance extending fromthe first flow face 320 to the second flow face 330. In this example,the plurality of flutes 340 are generally parallel. The plurality offlutes 340 can be upstream flutes or downstream flutes.

The plurality of flutes 340 defined by the plurality of sheets of filtermedia are arranged in a regularly alternating pattern of flute layers. Afirst flute layer 350 regularly alternates with a second flute layer360. The first flute layers 350 each have a first layer distance L₁between the first flow face 320 and the second flow face 330. Each ofthe second layers has a second layer distance L₂ between the first flowface 320 and the second flow face 330. In the current example, the firstlayer distance L₁ is less than the second layer distance L₂, but inother examples, the first layer distance L₁ is greater than the secondlayer distance L₂. The first layer distance L₁ and the second layerdistance L₂ generally differ by greater than 2 mm. In variousembodiments, the first layer distance L₁ differs from the second layerdistance L₂ by at least 5 mm. In some embodiments, the first layer L₁differs from the second layer distance L₂ by 3 mm to 20 mm. In someembodiments, the first layer distance L₁ differs from the second layerdistance L₂ by at least 8 mm. In some such embodiments, the first layerdistance L₁ differs from the second layer distance L₂ by at least 14 mm.

Each individual flute in the first flute layers 350 is defined by afluted sheet 352 and an adjacent facing sheet 354. Similarly, each ofthe second layers 360 is defined by a fluted sheet 362 and an adjacentfacing sheet 364. In the example of FIG. 7 each fluted sheet and facingsheet in each flute layer define substantially equal distances betweenthe first flow face 320 and the second flow face 330; however, in someembodiments, each fluted sheet and facing sheet in at least one flutelayer define distances that differ by greater than 2 mm. Also, in theembodiment of FIG. 7, each flute layer defines a substantially constantdistance between the first flow face 320 and the second flow face 330 inthe depth direction d (represented in FIG. 7 by an arrow); this meansthat the distance defined by each flute layer between the first flowface 320 and the second flow face 330 is equal to the flute distancebetween the first flow face 320 and the second flow face 330 for eachflute in the flute layer. In some embodiments, however, the distancedefined between the first flow face and the second flow face for one ormore sheets of filter media can vary in the depth direction, in whichcase the flute distances between the first flow face and the second flowface can be used to characterize the flute layers.

In some embodiments, including that depicted in FIG. 7, the plurality ofsheets of filter media further defines third flute layers 380 thatregularly alternate with the first flute layers 350 and second flutelayers 360. Each third flute layer 380 defines a third layer distance L₃between the first flow face 320 and the second flow face 330. In thecurrent embodiment, the third layer distance L₃ is greater than thefirst layer distance L₁ and the third layer distance L₃ is less than thesecond layer distance L₂, although other relative relationships arepossible, which has been described. In the presently-depicted example,the third layer distance L₃ differs from the first layer distance L₁ andthe second layer distance L₂ by greater than 2 mm.

Furthermore, in the current example of FIG. 7, the plurality of sheetsof filter media defines a regularly alternating pattern of fourth flutelayers 390, where each fourth flute layer defines a fourth layerdistance L₄ between the first flow face 320 and the second flow face330. The fourth layer distance L₄ is less than each of the first layerdistance L₁, the second layer distance L₂, and the third layer distanceL₃, although other relative relationships are possible, as previouslydescribed. The fourth layer distance L₄ differs from the first layerdistance L₁, the second layer distance L₂, and the third layer distanceL₃ by greater than 2 mm. Similar to the first flute layers 350 andsecond flute layers 360, the third flute layers 380 and the fourth flutelayers 390 have a fluted sheet 382, 392 and a facing sheet (notvisible), respectively. In alternative embodiments, additional or fewerflute layers can be incorporated in filter assemblies consistent withthe current technology. While in the current example (and the examplediscussed with reference to FIG. 9a , below) each regularly alternatinglayer defines a different distance between the first flow face 320 andthe second flow face 330, in some examples two or more regularlyalternating layers can define the same distance between the first flowface and the second flow face.

In various embodiments, a filter assembly that has layers and flow facesgenerally consistent with the description above with respect to FIG. 7can be incorporated in a two-stage separator system when modified todefine a central axis and an outer radial barrier surface between thefirst flow face and the second flow face. FIG. 8 depicts a schematiccross-sectional view of such a filter assembly 300 a, where thecross-section is perpendicular to the axial direction between the firstflow face and the second flow face. The filter assembly 300 a has acentral axis Z extending axially between the flow faces, and an outerradial barrier surface 359 extending about the central axis Z betweenthe first flow face such as the inlet flow face and the second flow facesuch as the outlet flow face (not currently depicted, but similar to asdepicted in FIG. 3). At least one of the flow faces (which can beconfigured to form an inlet flow face in a separator system) has anaxial flow face length L (that can be the same as the flow face lengthin FIG. 7).

To achieve a configuration consistent with FIG. 8, in some examples thesides extending between the first flow face and the second flow face ofthe panel filter assembly 300 consistent with FIG. 7 can be cut usinglaser cutting or a sharp edge to form the circular cross-section. Toencourage spiraling airflow about the filter element towards the secondend of the separator housing (as described above with reference to FIG.2), a sleeve can define the outer radial barrier surface 359 of thefilter assembly 300 a. The sleeve can be consistent with sleevesdiscussed above with reference to FIG. 2.

The examples depicted and described in association with FIGS. 9A-13,below, also depict panel filter assemblies. Similar to the discussionabove with respect to FIG. 8, each of these panel filter assemblies canbe configured to be incorporated in a two-stage separator system by (1)configuring the sides of the panels between the flow faces to form acircular cross-sectional shape having a central axis and (2)incorporating a sleeve (for example) to define an outer radial barriersurface extending between the inlet flow face and the outlet flow face.In such embodiments, at least one flow face has an axial length.

FIG. 9a depicts a perspective view of another example filter assembly400 consistent with the technology disclosed herein, and FIG. 9b depictsa facing view at a first flow face 420 of the example filter assembly400. The filter assembly 400 is a panel filter assembly. The filterassembly 400 is constructed of filter media 410 defining the first flowface 420, a second flow face 430, and a plurality of flutes 440extending from the first flow face 420 to the second flow face 430 in anaxial direction. The first flow face 420 is defined on a first end 402of the filter assembly 400 and the second flow face 430 is defined on asecond, opposite end 404 of the filter assembly 400. In the currentexample of FIG. 8, both the first flow face 420 is non-planar and thesecond flow face 430 is non-planar, but in some other embodiments, onlyone of the first flow face 420 and the second flow face 430 isnon-planar and the other of the first flow face 420 and the second flowface 430 is planar. Each of the first flow face 420 and the second flowface 430 has a flow face length L_(A1), L_(A2), respectively. Neitherthe first flow face 420 nor the second flow face 430 define a taper forat least a portion of its respective axial flow face length.

The filter media 410 is a plurality of sheets of filter media. Inparticular, the plurality of sheets of filter media has fluted sheets offilter media. The plurality of sheets of filter media are in a stackedconfiguration. The plurality of sheets of filter media are continuousrelative to each other. Each sheet of filter media has a first fold 412defining the first flow face 420 of the filter assembly 400. In thecurrent embodiment, each sheet of filter media has a second fold 414defining the second flow face 430 of the filter assembly 400. Theplurality of sheets of filter media 410 cumulatively define theplurality of flutes 440. Each of the plurality of flutes 440 defines aflute opening 442 and a flute closure 470, where the flute closures 470are defined between pairs of the first folds 412 at the first flow face420 and pairs of the second folds 414 at the second flow face 430. Insome alternative embodiments the flute closure can be defined by asingle fold line that separates adjacent sheets of filter media. In thisexample, the plurality of flutes 440 are generally parallel. Theplurality of flutes 440 can be upstream flutes or downstream flutes.

The plurality of sheets of filter media define a regularly alternatingpattern of first flute layers 450 and second flute layers 460. The firstflute layers 450 each have a first layer distance L₁ between the firstflow face 420 and the second flow face 430. Each of the second flutelayers 460 has a second layer distance L₂ between the first flow face420 and the second flow face 430. The second layer distance L₂ is lessthan the first layer distance L₁ in the current example, although insome embodiments the second layer distance L₂ is greater than the firstlayer distance L₁. The first layer distance L₁ and the second layerdistance L₂ generally differ by greater than 2 mm. In variousembodiments, the first layer distance L₁ differs from the second layerdistance L₂ by at least 5 mm. In some embodiments, the first layer L₁differs from the second layer distance L₂ by 4 mm to 20 mm. In someembodiments, the first layer distance L₁ differs from the second layerdistance L₂ by at least 8 mm. In some such embodiments, the first layerdistance L₁ differs from the second layer distance L₂ by at least 14 mm.

Each of the first flute layers 450 is defined by a first fluted sheet452 and an adjacent second fluted sheet 454. Similarly, each of thesecond flute layers 460 is defined by a third fluted sheet 462 and anadjacent fourth fluted sheet 464. Similar to the embodiment describedabove with respect to FIG. 7, in the current embodiment of FIG. 9 a,each flute layer defines a substantially constant distance between thefirst flow face 420 and the second flow face 430 in the depth directiond₂; this means that the distance defined by each flute layer is equal tothe flute distance between the first flow face 420 and the second flowface 430 of each flute in the flute layer. In some embodiments, however,the distance that one or more sheets of filter media defines between thefirst flow face 420 and the second flow face 430 can vary in the depthdirection d₂.

Additional alternating flute layers can be incorporated into filterassemblies consistent with the technology disclosed herein, similar tothe previous example reflected in FIG. 7.

FIG. 10 depicts a perspective view of yet another example filterassembly 700 consistent with the technology disclosed herein. The filterassembly 700 is a panel filter that is constructed of a plurality ofsheets of filter media 710 in a stacked configuration that cumulativelydefine a first plurality of flutes 740, a first flow face 720 and asecond flow face 730 opposite the first flow face relative to the filterassembly 700. The plurality of stacked sheets of filter media 710 arealternating fluted sheets of filter media and facing sheets of filtermedia. The plurality of stacked sheets of filter media 710 arediscontinuous. In various embodiments, at least one of the first flowface 720 and the second flow face 730 is non-planar. In the currentexample, the first flow face 720 defines a flow face length L. The firstflow face 720 defines a taper for at least a portion of the axial flowface length L. The taper increases for at least a portion of the axialflow face length and the taper continuously changes along the axial flowface length.

Each of the first plurality of flutes 740 defines a flute opening 742 atthe first flow face 720 and a flute closure 744 towards the second flowface 730. In some embodiments, at least one flute 745 of the pluralityof flutes 740 defines a flute opening 742 that is non-planar. Each ofthe first plurality of flutes 740 defines a flute distance from thefirst flow face 720 to the second flow face 730. Each sheet of filtermedia 710 can be characterized as having a width extending in adirection parallel to an x-axis and a length extending in a directionparallel to a z-axis. The plurality of sheets of filter media 710 arestacked in a direction parallel to a y-axis.

In a number of embodiments, the filter assembly 700 at least has a firstsheet of filter media 750 and a second sheet of filter media 760mutually defining the first flow face 720, the second flow face 730, anda portion of the first plurality of flutes 740. In this example thefirst sheet of filter media 750 is a fluted sheet and the second sheetof filter media 760 is a facing sheet. A first flute 741 of the firstplurality of flutes 740 defines a first flute distance d₁ and a secondflute 743 of the first plurality of flutes 740 defines a second flutedistance d₂. In the current example, the first flute distance d₁ isgreater than the second flute distance d₂, although in some otherexamples, the first flute distance d₁ is less than the second flutedistance d₂. The first flute distance d₁ and the second flute distanced₂ differ by greater than 2 mm. In some embodiments the first flutedistance d₁ and the second flute distance d₂ differ by at least 5 mm. Insome embodiments the first flute distance d₁ and the second flutedistance d₂ differ by 3 mm to 20 mm. In some embodiments the first flutedistance d₁ and the second flute distance d₂ differ by at least 8 mm. Insome embodiments the first flute distance d₁ and the second flutedistance d₂ differ by at least 15 mm.

The filter assembly 700 also has a third sheet of filter media 770,where the third sheet of filter media and the second sheet of filtermedia 760 mutually define a second plurality of flutes 780, the firstflow face 720 and the second flow face 730. Each of the second pluralityof flutes 780 extends from the first flow face 720 to the second flowface 730. Each of the second plurality of flutes 780 defines a fluteopening at the second flow face 730 (not visible in this view) and aflute closure towards the first flow face 720. The flute closure can bean obstruction disposed between the second sheet of filter media 760 andthe third sheet of filter media 770 towards the first flow face 720. Thesecond plurality of flutes 780 can have a third flute 747 that defines athird flute distance d₃ between the first flow face 720 and the secondflow face 730. In the current example, the third flute distance d₃ isgreater than the first flute distance d₁ and the second flute distanced₂, although alternate relative relationships among the flute distancesare contemplated, as well, which has been previously discussed. Thefirst flute distance d₁ differs from the third flute distance d₃ bygreater than 2 mm. In some embodiments, each of the first flute distanced₁, second flute distance d₂, and third flute distance d₃ differ bygreater than 2 mm. In some embodiments the first flute distance d₁differs from the second flute distance d₂ and the third flute distanced₃ by amounts and ranges previously described herein.

In the current example of FIG. 10, the second flute 743 is adjacent thefirst flute 741 in the x-axis direction, although in some otherembodiments the second flute 743 is not adjacent the first flute 741. Insome embodiments, the third flute 747 is positioned relative to thefirst flute 741 in the y-axis direction, but in other embodiments thethird flute 747 is not positioned relative to the first flute 741 in they-axis direction. In some alternative embodiments the third flute 747can be a flute in the first plurality of flutes 740.

In the current example, the first flow face 720 is non-planar and thesecond flow face 730 is planar. In an alternative example embodiment,both the first flow face and the second flow face are non-planar. Insome embodiments, the first flow face and the second flow face areplanar and non-parallel to each other. In various embodiments, theplurality of flutes 740 are parallel, although in some embodiments, theplurality of flutes 740 are not parallel.

Similar to the embodiments depicted in FIGS. 3-4 b, the filter assembly700 is generally constructed to define a fluid pathway 718 between thefirst flow face 720 and the second flow face 730 through the filtermedia 710 such that the fluid is filtered by the filter media 710.

In various embodiments, at least one of the first flow face 720 and thesecond flow face 730 is planar. In examples consistent with theparticular embodiment of FIG. 10, the first flow face 720 is planar andthe second flow face 730 is planar, and the first flow face 720 isnon-parallel to the second flow face 730. In alternative embodiments oneor both of the first flow face and the second flow face can benon-planar. For example, one or both of the first flow face and thesecond flow face can be cut to be a three-dimensional surface.

FIG. 11 depicts a perspective view of yet another example filterassembly 800 consistent with the technology disclosed herein. The filterassembly 800 is a panel filter that is constructed of a plurality ofsheets of filter media 810 in a stacked configuration that define afirst plurality of flutes 840, a first flow face 820 and a second flowface 830 opposite the first flow face relative to the filter assembly800. The plurality of stacked sheets of filter media 810 are flutedsheets of filter media. The plurality of stacked sheets of filter media810 are discontinuous. In various embodiments, at least one of the firstflow face 820 and the second flow face 830 is non-planar, and in thecurrent embodiment, both the first flow face 820 and the second flowface 830 are non-planar. Each of the first flow face 820 and the secondflow face 830 has an axial flow face length (see L, for example). Eachof the first flow face 820 and the second flow face 830 defines a taperin the axial direction.

The plurality of sheets of filter media 810 cumulatively define aplurality of flutes 840. Each of the first plurality of flutes 840defines a flute opening 842 at the first flow face 820 and a fluteclosure (not shown) towards the second flow face 830, where the fluteclosure is similar to those described above and depicted at least inFIGS. 4a and 6b . In some embodiments, at least one flute 845 of theplurality of flutes 840 defines a flute opening 842 that is non-planar.Each of the first plurality of flutes 840 defines a flute distance fromthe first flow face 820 to the second flow face 830. Each sheet offilter media 810 can be characterized as having a width extending in adirection parallel an x-axis and a length extending in a directionparallel to a z-axis. The plurality of sheets of filter media 810 arestacked in a direction parallel to a y-axis.

In a number of embodiments, the filter assembly 800 at least has a firstsheet of filter media 850 and a second sheet of filter media 860mutually defining the first flow face 820, the second flow face 830, anda portion of the first plurality of flutes 840. In this example both thefirst sheet of filter media 850 and the second sheet of filter media 860are fluted sheets. A first flute 841 of the portion of the firstplurality of flutes 840 defines a first flute distance d₁ and a secondflute 843 of the first plurality of flutes 840 defines a second flutedistance d₂. In the current example, the first flute distance d₁ isgreater than the second flute distance d₂, although in some otherexamples, the first flute distance d₁ is less than the second flutedistance d₂. The first flute distance d₁ and the second flute distanced₂ differ by greater than 2 mm and can further differ by amounts andranges previously discussed.

The filter assembly 800 also has a third sheet of filter media 870,where the third sheet of filter media and the second sheet of filtermedia 860 mutually define a second plurality of flutes 880, the firstflow face 820 and the second flow face 830. Each of the second pluralityof flutes 880 extends from the first flow face 820 to the second flowface 830. Each of the second plurality of flutes 880 defines a fluteopening at the second flow face 830 (not visible in this view) and aflute closure towards the first flow face 820. The flute closure can bean obstruction disposed between the second sheet of filter media 860 andthe third sheet of filter media 870 towards the first flow face 820.

The second plurality of flutes 880 can have a third flute 847 thatdefines a third flute distance d₃ between the first flow face 820 andthe second flow face 830. In the current example, the third flutedistance d₃ is greater than the first flute distance d₁ and the secondflute distance d₂, although alternate relative relationships among theflute distances are contemplated. The first flute distance d₁ differsfrom the third flute distance d₃ by greater than 2 mm. In someembodiments, each of the first flute distance d₁, second flute distanced₂, and third flute distance d₃ differ by greater than 2 mm. In someembodiments the first flute distance d₁ differs from the second flutedistance d₂ and the third flute distance d₃ by amounts and rangespreviously described herein.

In the current example the second flute 843 is adjacent the first flute841 in the x-axis direction, although in some other embodiments thesecond flute 843 is not adjacent the first flute 841. In someembodiments, the third flute 847 is positioned relative to the firstflute 841 in the y-axis direction, but in other embodiments the thirdflute 847 is not positioned relative to the first flute 841 in they-axis direction. In some alternative embodiments the third flute 847can be a flute in the first plurality of flutes 840.

In the current example, the first flow face 820 is non-planar and thesecond flow face 830 is non-planar. In particular, the first flow face820 is recessed relative to the filter assembly 800. Similarly, thesecond flow face 830 is recessed relative to the filter assembly. In analternative example, both the first flow face and the second flow faceare planar and non-parallel to each other. In some embodiments, thefirst plurality of flutes 840 are parallel, although in someembodiments, the first plurality of flutes 840 are not parallel.

Similar to the embodiments described above, the filter assembly 800 isgenerally constructed to define a fluid pathway 818 between the firstflow face 820 and the second flow face 830 through the filter media 810such that the fluid is filtered by the filter media 810.

The example filter assemblies described and depicted in FIGS. 9 and 10can be constructed through a variety of different approaches. In atleast one embodiment, flute obstructions are deposited between theadjacent sheets of filter media at relevant locations and the sheets offilter media are stacked. The stacked media is then cut with a cuttingtool (examples of which have been mentioned above with respect FIG. 5)to form the first flow face and/or the second flow face into the desiredconfiguration. In an alternative embodiment, the edges of the sheets offilter media corresponding to flow faces are cut to the desiredconfiguration, and the cut sheets of media are then stacked to form intoa filter assembly. The flute obstructions can be deposited on the sheetsof filter media before or after the sheets of filter media are cut.

FIG. 12 depicts a perspective view of yet another example filterassembly 900 consistent with the technology disclosed herein. The filterassembly 900 is a panel filter that is constructed of a plurality ofsheets of filter media 910 in a stacked configuration that define afirst plurality of flutes 940, a first flow face 920 of the filterassembly 900 and a second flow face 930 opposite the first flow face 920relative to the filter assembly 900. The plurality of sheets of filtermedia 910 are fluted sheets of filter media. In various embodiments, atleast one of the first flow face 920 and the second flow face 930 isnon-planar, and in the current embodiment, the first flow face 920 isnon-planar and the second flow face 930 is planar. The first flow face920 has an axial flow face length L extending in an axial direction Z.The first flow face 920 defines a taper for at least a portion of theaxial flow face length.

The plurality of sheets of filter media 910 are continuous relative toeach other. Each sheet of filter media has a first fold 912 defining thefirst flow face 920 of the filter assembly 900. Each sheet of filtermedia 910 has a second fold 914 (only a small portion of which isvisible) defining the second flow face 930 of the filter assembly 900.Each of the first plurality of flutes 940 defines a flute opening 942 atthe first flow face 920 and a flute closure 916 towards the second flowface 930. The flute closure 916 is defined by the filter media on thesecond flow face 930, where the filter media extends between adjacentsecond folds 914 on the second flow face 930.

In some embodiments, at least one flute 945 of the plurality of flutes940 defines a flute opening 942 that is non-planar. Each of the firstplurality of flutes 940 defines a flute distance from the first flowface 920 to the second flow face 930. Each sheet of filter media 910 canbe characterized as having a width extending in a direction parallel toan x-axis and a length extending in a direction parallel to a z-axis.The plurality of sheets of filter media 910 are stacked in a directionparallel to a y-axis.

In a number of embodiments, the filter assembly 900 at least has a firstsheet of filter media 950 and a second sheet of filter media 960mutually defining the first flow face 920, the second flow face 930, anda portion of the first plurality of flutes 940. In this example both thefirst sheet of filter media 950 and the second sheet of filter media 960are fluted sheets. A first flute 941 of the portion of the firstplurality of flutes 940 defines a first flute distance d₁ and a secondflute 943 of the first plurality of flutes 940 defines a second flutedistance d₂. In the current example, the first flute distance d₁ is lessthan the second flute distance d₂, although in some other examples, thefirst flute distance d₁ is greater than the second flute distance d₂.The first flute distance d₁ and the second flute distance d₂ differ bygreater than 2 mm and can further differ by amounts and rangespreviously discussed.

The filter assembly 900 also has a third sheet of filter media 970,where the third sheet of filter media and the second sheet of filtermedia 960 mutually define a second plurality of flutes 980, the firstflow face 920 and the second flow face 930. Each of the second pluralityof flutes 980 extends from the first flow face 920 to the second flowface 930. Each of the second plurality of flutes 980 defines a fluteopening at the second flow face 930 (not visible in this view) and aflute closure 916 towards the first flow face 920. The flute closure canbe an obstruction disposed between the second sheet of filter media 960and the third sheet of filter media 970 towards the first flow face 920.In the current embodiment the flute closure 916 is a portion of filtermedia defined by one or more folds 912, similar to as described withrespect to FIGS. 9a and 9b . The second plurality of flutes 980 can havea third flute 981 that defines a third flute distance d₃ between thefirst flow face 920 and the second flow face 930. In the currentexample, the third flute distance d₃ is greater than the first flutedistance d₁ and the second flute distance d₂ (although not clear fromthe current viewing angle), although alternate relative relationshipsamong the flute distances are contemplated. The first flute distance d₁differs from the third flute distance d₃ by greater than 2 mm. In someembodiments, each of the first flute distance d₁, second flute distanced₂, and third flute distance d₃ differ by greater than 2 mm. In someembodiments the first flute distance d₁ differs from the second flutedistance d₂ and the third flute distance d₃ by amounts and rangespreviously described herein.

In the current example of FIG. 12, the second flute 943 is adjacent thefirst flute 941 in the x-axis direction, although in some otherembodiments the second flute 943 is not adjacent the first flute 941. Insome embodiments, the third flute 981 is positioned relative to thefirst flute 941 in the y-axis direction, but in other embodiments thethird flute 981 is not positioned relative to the first flute 941 in they-axis direction. In some alternative embodiments the third flute 981can be a flute in the first plurality of flutes 940.

In the current example of FIG. 12, the first flow face 920 is non-planarand the second flow face 930 is planar. In an alternative exampleembodiment, both the first flow face and the second flow face are planarand non-parallel to each other. In some embodiments, the first pluralityof flutes 940 are parallel, although in some alternative embodiments,the first plurality of flutes 940 are not parallel. Also, while in thecurrent embodiment the filter media is pleated, in some otherembodiments the media is not pleated.

Similar to the embodiments described above, the filter assembly 900 isgenerally constructed to define a fluid pathway 918 between the firstflow face 920 and the second flow face 930 through the filter media 910such that the fluid is filtered by the filter media 910.

FIG. 13 depicts a perspective view of yet another example filterassembly 1000 consistent with the technology disclosed herein. Thefilter assembly 1000 is a panel filter that is constructed of aplurality of sheets of filter media 1010 in a stacked configuration thatdefine a first plurality of flutes 1040, a first flow face 1020 of thefilter assembly 1000 and a second flow face 1030 opposite the first flowface 1020 relative to the filter assembly 1000. The plurality of sheetsof filter media 1010 are fluted sheets of filter media. In the currentembodiment, the first flow face 1020 is planar and the second flow face1030 is planar, and the first flow face 1020 is non-parallel to thesecond flow face 1030. The first flow face 1020 has a flow face lengthL. The first flow face 1020 defines a taper for at least a portion ofthe axial flow face length.

The plurality of sheets of filter media 1010 are continuous relative toeach other. Each sheet of filter media has a first fold 1012 definingthe first flow face 1020 of the filter assembly 1000. Each sheet offilter media 1010 has a second fold 1014 (only a small portion of whichis visible) defining the second flow face 1030 of the filter assembly1000. Each of the first plurality of flutes 1040 defines a flute opening1042 at the first flow face 1020 and a flute closure 1016 towards thesecond flow face 1030. The flute closure 1016 is defined by the filtermedia on the second flow face 1030, where the filter media extendsbetween adjacent second folds 1014 on the second flow face 1030. Theflute closure 1016 can be similar to that described in the discussion ofFIGS. 9a and 9 b.

Each of the first plurality of flutes 1040 defines a flute distance fromthe first flow face 1020 to the second flow face 1030. Each sheet offilter media 1010 can be characterized as having a width extending in adirection parallel to an x-axis and a length extending in a directionparallel to a z-axis. The plurality of sheets of filter media 1010 arestacked in a direction parallel to a y-axis.

In a number of embodiments, the filter assembly 1000 at least has afirst sheet of filter media 1050 and a second sheet of filter media 1060mutually defining the first flow face 1020, the second flow face 1030,and a portion of the first plurality of flutes 1040. In this exampleboth the first sheet of filter media 1050 and the second sheet of filtermedia 1060 are fluted sheets. A first flute 1041 of the portion of thefirst plurality of flutes 1040 defines a first flute distance d₁ and asecond flute 1043 of the first plurality of flutes 1040 defines a secondflute distance d₂. In the current example, the first flute distance d₁is less than the second flute distance d₂, although in some otherexamples, the first flute distance d₁ is greater than the second flutedistance d₂. The first flute distance d₁ and the second flute distanced₂ differ by greater than 2 mm and can further differ by amounts andranges previously discussed.

The filter assembly 1000 also has a third sheet of filter media 1070,where the third sheet of filter media and the second sheet of filtermedia 1060 mutually define a second plurality of flutes 1080, the firstflow face 1020 and the second flow face 1030. Each of the secondplurality of flutes 1080 extends from the first flow face 1020 to thesecond flow face 1030. Each of the second plurality of flutes 1080defines a flute opening at the second flow face 1030 (not visible inthis view) and a flute closure 1016 towards the first flow face 1020.The flute closure can be an obstruction disposed between the secondsheet of filter media 1060 and the third sheet of filter media 1070towards the first flow face 1020. In the current embodiment the fluteclosure 1016 is a portion of filter media defined by one or more folds1012.

The second plurality of flutes 1080 can have a third flute 1081 thatdefines a third flute distance d₃ between the first flow face 1020 andthe second flow face 1030. In the current example, the third flutedistance d₃ is less than the first flute distance d₁ and the secondflute distance d₂, but in some embodiments the third flute distance d₃is greater than one or both of the first flute distance d₁ and thesecond flute distance d₂ The first flute distance d₁ differs from thethird flute distance d₃ by greater than 2 mm. In some embodiments, eachof the first flute distance d₁, second flute distance d₂, and thirdflute distance d₃ differ by greater than 2 mm. In some embodiments thefirst flute distance d₁ differs from the second flute distance d₂ andthe third flute distance d₃ by amounts and ranges previously describedherein.

In the current example of FIG. 13, the second flute 1043 is adjacent thefirst flute 1041 in the x-axis direction, although in some otherembodiments the second flute 1043 is not adjacent the first flute 1041.In some embodiments, the third flute 1081 is positioned relative to thefirst flute 1041 in the y-axis direction, but in other embodiments thethird flute 1081 is not positioned relative to the first flute 1041 inthe y-axis direction. In some alternative embodiments the third flute1081 can be a flute in the first plurality of flutes 1040.

In some embodiments, the first plurality of flutes 1040 are parallel,although in some embodiments, the first plurality of flutes 1040 are notparallel. Also, while in the current embodiment the filter media ispleated, in some other embodiments the pleated media is not pleated andobstructions are positioned between sheets of filter media to close offends of flutes.

Similar to the embodiments described above, the filter assembly 1000 isgenerally constructed to define a fluid pathway 1018 between the firstflow face 1020 and the second flow face 1030 through the filter media1010 such that the fluid is filtered by the filter media 1010.

FIG. 14A depicts one example filter assembly consistent with thetechnology disclosed herein. The filter assembly 500 is constructed offilter media 510 defining a first flow face 520, a second flow face 530,and a plurality of flutes 540 extending from the first flow face 520 tothe second flow face 530 in an axial direction Z. In the currentexample, the first flow face 520 is defined on a first end 502 of thefilter assembly 500 and the second flow face 530 is defined on a second,opposite end 504 of the filter assembly 500. The first flow face 520 hasan axial flow face length L and defines a taper for at least a portionof the axial flow face length.

The filter media 510 is a plurality of sheets of filter media,specifically a first sheet of filter media 512 and a second sheet offilter media 514. The second sheet of filter media 514 is visible inFIG. 14B, which depicts a portion of the filter media 510 in a flat,uncoiled arrangement, distinguished from the coiled filter media 510 inthe filter assembly 500 consistent with FIG. 14A. FIG. 14B is a facingview of the second sheet of filter media 514. The second sheet of filtermedia 514 is adjacent to the first sheet of filter media 512. The firstsheet of filter media 512 and the second sheet of filter media 514mutually define the plurality of flutes 540. The filter media 510defines a coiled configuration about a Z-axis. Accordingly, each of thefirst sheet of filter media 512 and the second sheet of filter media 514defines a coiled configuration around the Z-axis. As such, the pluralityof flutes 540 are also in a coiled configuration about the Z-axis.

In the current example, the first sheet of filter media 512 and thesecond sheet of filter media 514 are coiled about a rod 585. As such,the rod 585 extends centrally through the filter assembly 500. The rod585 has a proximal end positioned towards the second flow face 530 and adistal end positioned towards the first flow face 520, where the secondflow face 530 can be an outlet flow face and the first flow face 520 canbe an inlet flow face 520. The rod 585 defines a handle 586 on thedistal end that is configured to be grasped by a user duringinstallation and removal of the filter assembly 500 in a two-stageseparator system (see. FIGS. 1 and 2). In such embodiments, theseparator system can define a centering feature that is configured toreceive the handle 586, such as described above with reference to FIG.2. In some embodiments the handle can be omitted from the filterelement. In some embodiments both the handle and the rod is omitted fromthe filter element.

As visible in FIG. 14B, the filter media 510 (particularly the firstsheet of filter media 512 and the second sheet of filter media 514) aregenerally elongate, which enables the first sheet of filter media 512and the second sheet of filter media 514 to be coiled about the Z-axisto form a filter assembly. In this example, the first sheet of filtermedia 512 and the second sheet of filter media 514 are discontinuous.The first sheet of filter media 512 defines a first edge 511 and asecond edge 513 (FIG. 14A). The second sheet of filter media 514 definesa third edge 515 and a fourth edge 517 (FIG. 14B). The first edge 511and the third edge 515 mutually define the first flow face 520 of thefilter assembly 500. The second edge 513 and the fourth edge 517mutually define the second flow face 530 of the filter assembly 500. Thefirst edge 511 and third edge 515 each individually form an undulatingor wavy line. The second edge 513 and the fourth edge 517 eachindividually form a straight line. The filter media 510 in examplesconsistent with the current embodiment has four edges. The shape of thefilter media 510 is generally non-rectangular and non-trapezoidal due tothe undulating/wavy edge. In particular, the first edge 511 and thirdedge 515 mutually define multiple concave and convex shapes.

In examples consistent with the current embodiment, the first sheet offilter media 512 is fluted, and the second sheet of filter media 514 isa facing sheet. In the current embodiment the plurality of flutes areparallel, but in some other embodiments the plurality of flutes are notparallel.

The filter assembly 500 is generally constructed to define a fluidpathway 506 between the first flow face 520 and the second flow face 530through the filter media 510 such that the fluid is filtered by thefilter media 510. In particular, the plurality of flutes 540 defineseither inlet flutes, or outlet flutes, similar to as described in FIG.3.

Each of the plurality of flutes 540 defines a flute opening 542 and aflute closure (not visible). The flute opening 542 forms an end-mostportion of the fluid pathway 506 along the flutes to accommodate fluidflow into or out of the filter assembly 500. The flute closure obstructsfluid flow along the flute, thereby defining a portion of the fluidpathway 506 through the filter media 510. So, for example, a pluralityof inlet flutes can define the flute opening 542 at the first flow face520 and a flute closure is defined across the plurality of inlet flutestowards the second flow face 530. In some embodiments, the flute closureis adjacent to the second flow face 530. More particularly, the fluteclosure can abut the second flow face 530. The flute closure can besimilar to flute closures discussed above.

In the current embodiment, the volume defined between an outer surface516 of the first sheet of filter media 512 (FIG. 14A) and an outersurface 518 of the second sheet of filter media 514 (FIG. 14B) when thefilter media is coiled (FIG. 14A) defines a fluid pathway 506 that isnot necessarily characterized as being defined by a plurality of flutes.

An obstruction can be disposed within the coil and outside of theplurality of flutes 540 such that fluids passing through the first flowface 520 and second flow face 530 of the filter assembly 500 must firstpass through the filter media 510. Additional obstructions can also bedisposed in any other gaps in the filter media to prevent fluid flowthere-through, such as around the outer perimeter of the filter assembly500 and in a central opening of the filter assembly 500. An obstructioncan be formed through depositing an adhesive, such as a glue bead at therelevant location.

Each of the plurality of flutes 540 defines a flute distance between thefirst flow face 520 and the second flow face 530. In the currentembodiment, a first flute 544 of the plurality of flutes 540 defines afirst flute distance D₁ between the first flow face 520 and the secondflow face 530 and a second flute 546 of the plurality of flutes 540defines a second flute distance D₂ between the first flow face 520 andthe second flow face 530. In some examples, the first flute distance D₁is less than the second flute distance D₂, as currently depicted. Insome other examples, the first flute distance D₁ is greater than thesecond flute distance D₂. In certain embodiments, the first flutedistance D₁ and the second flute distance D₂ differ by greater than 2mm. In some embodiments, the first flute distance D₁ differs from thesecond flute distance D₂ by at least 5 mm, at least 8 mm or even atleast 15 mm. In some embodiments, the first flute distance D₁ differsfrom the second flute distance D₂ by 3 mm to 520 mm, 510 mm to 520 mm,or 15 mm to 25 mm.

In some embodiments, a third flute 548 of the plurality of flutes 540defines a third flute distance D₁ between the first flow face 520 andthe second flow face 530. The third flute distance D₁ will generallydiffer from at least one of the first flute distance D₁ and the secondflute distance D₂ by greater than 2 mm. In some embodiments the thirdflute distance D₁ differs from both the first flute distance D₁ and thesecond flute distance D₂ by greater than 2 mm. The third flute distanceD₁ can differ from one or both the first flute distance D₁ and thesecond flute distance D₂ by similar ranges described above. In thecurrent example, the third flute distance D₁ is greater than the firstflute distance D₁ and less than the second flute distance D₂.

The differences in flute distances between the first flow face 520 ofthe filter assembly 500 and the second flow face 530 of the filterassembly 500 is also evidenced by the shapes of the flow faces relativeto each other. In various embodiments, at least one of the first flowface 520 and the second flow face 530 is non-planar. In variousembodiments, at least one of the first flow face 520 and the second flowface 530 is substantially planar. In examples consistent with thisparticular embodiment, the first flow face 520 is non-planar and thesecond flow face 530 is planar. Further, in this particular embodiment,the first flow face 520 is configured such that it protrudes outwardfrom the filter assembly in the axial direction Z. The shape of thefirst flow face 520 is generally asymmetric relative to the Z-axis.

FIGS. 26a and 26b depict example cross-sections of an example filterassembly 500 installed in a housing similar to the housing 1910 depictedin FIGS. 1-2, where the cross-sections are perpendicular to a z-axisthat is central to the housing 1910 and the filter assembly 500. Thefilter assembly 500 has a first flow face 520 that does not reflectflute profile shapes. FIG. 26a is a first cross section taken at a firstposition P₁ along the axial length of the first flow face 520 and FIG.26b is a second cross section taken at a second position P₂ along theaxial length of the first flow face 520. The annulus defined between thefirst flow face 520 and the housing 1910 in a cross-sectionperpendicular to the z-axis has an increasing area A along at least aportion of the length of the first flow face 520 from a first side tothe second side of the housing 1910. In particular, the area of theannulus A₁ defined between first flow face 520 and the housing 1910 inFIG. 26a at position P₁ is less than the area of the annulus A₂ atposition P₂.

Furthermore, the radial distances R_(1,2) defined between the first flowface 520 and the housing 1910 relative to the central axis z at thefirst position P₁ and the second position P₂ along the axial length ofthe inlet flow face 520 are different. The second radial distance R₂ isgreater than the first radial distance R₁, where the first radialdistance R₁ and the second radial distance R₂ are in axial alignment andin parallel.

It will be appreciated that, in some alternative embodiments, the firstflow face 520 can be planar and the second flow face 530 can benon-planar. In some embodiments at least one flute in the plurality offlutes 540 defines a flute opening that is non-planar.

In examples consistent with the current embodiment, an obstruction 549is disposed adjacent to the fourth edge 517 of the second sheet offilter media 514 along the length of the second sheet of filter media514. The fourth edge 517 of the second sheet of filter media 514 isgenerally planar when the filter media 510 is in a coiled configuration.Here the obstruction 549 also is generally planar when the filter media510 is in a coiled configuration.

FIG. 15A depicts an example filter assembly 550 consistent with thetechnology disclosed herein, and FIG. 15B depicts a facing view ofcorresponding filter media 560, which is in an uncoiled, or planararrangement. The filter assembly 550 is constructed of filter media 560defining a first flow face 570, a second flow face 580, and a pluralityof flutes 590 extending from the first flow face 570 to the second flowface 580. In the current example, the first flow face 570 is defined ona first end 552 of the filter assembly 550 and the second flow face 580is defined on a second, opposite end 554 of the filter assembly 550. Thefirst flow face 570 has an axial flow face length L and the first flowface 570 defines a taper for at least a portion of the axial flow facelength L.

The filter media 560 is a plurality of sheets of filter media,specifically a first sheet of filter media 562 and a second sheet offilter media 564. The second sheet of filter media 564 is visible inFIG. 15B, which is a portion of the filter media 560 in a flat, uncoiledarrangement, distinguished from the coiled filter media 560 forming thefilter assembly 550 consistent with FIG. 15A. FIG. 15B is a facing viewof the second sheet of filter media 564. The second sheet of filtermedia 564 is adjacent to the first sheet of filter media 562. The firstsheet of filter media 562 and the second sheet of filter media 564mutually define the plurality of flutes 590. The filter media 562 canhave a variety of configurations, some examples of which are describedin association with FIGS. 6a-6d , and also described below. In thecurrent embodiment the plurality of flutes are parallel, but in someother embodiments the plurality of flutes are not parallel.

The filter media 560 defines a coiled configuration about a Z-axis.Accordingly, each of the first sheet of filter media 562 and the secondsheet of filter media 564 defines a coiled configuration around theZ-axis. As such, the plurality of flutes 590 are also in a coiledconfiguration about the Z-axis.

As visible in FIG. 15B, the filter media 560 (particularly the firstsheet of filter media 562 and the second sheet of filter media 564) aregenerally elongate, which enables the first sheet of filter media 562and the second sheet of filter media 564 to be coiled about the Z-axisto form a filter assembly. In this example, the first sheet of filtermedia 562 and the second sheet of filter media 564 can be continuous ordiscontinuous. In embodiments where the sheets are discontinuous, thefirst sheet of filter media 562 defines a first edge 561 and a secondedge 563 (FIG. 15A) and the second sheet of filter media 564 defines athird edge 565 and a fourth edge 567 (FIG. 15B). The first edge 561 andthe third edge 565 mutually define the first flow face 570 of the filterassembly 550. The second edge 563 and the fourth edge 567 mutuallydefine the second flow face 580 of the filter assembly 550. The secondedge 593 and the fourth edge 567 each individually form a straight linethat defines the edge of the filter media 564.

The first edge 561 and third edge 565 mutually and individually form astepped line. The stepped line has horizontal segments 572 joined byvertical segments 574. The shape of the filter media 564 is generallynon-rectangular and non-trapezoidal based on the stepped edge.

The filter assembly 550 is generally constructed to define a fluidpathway 556 between the first flow face 570 and the second flow face 580through the filter media 560 such that the fluid is filtered by thefilter media 560. In particular, the plurality of flutes 590 defineseither inlet flutes or outlet flutes, similar to as described above.

Each of the plurality of flutes 590 defines a flute opening 592 and aflute closure (not visible). The flute opening 592 forms an end-mostportion of the fluid pathway 556 along the flutes to accommodate fluidflow into or out of the filter assembly 550. The flute closure obstructsfluid flow along the flute, thereby defining a portion of the fluidpathway 556 through the filter media 560. So, for example, a pluralityof inlet flutes can define the flute opening 592 at the first flow face570 and a flute closure is defined across the plurality of inlet flutestowards the second flow face 580. In some embodiments, the flute closureis adjacent to the second flow face 580. More particularly, the fluteclosure can abut the second flow face 580. The flute closure can besimilar to flute closures discussed above.

In the current embodiment, the volume defined between an outer surface566 of the first sheet of filter media 562 (FIG. 15A) and an outersurface 568 of the second sheet of filter media 564 (FIG. 15B) when thefilter media is coiled (FIG. 15A) defines a fluid pathway 556 that isnot necessarily characterized as being defined by a plurality of flutes.

An obstruction can be disposed within the coil and outside of theplurality of flutes 590 such that fluids passing through the first flowface 570 and second flow face 580 of the filter assembly 550 must firstpass through the filter media 560. Additional obstructions can also bedisposed in any other gaps in the filter media to prevent fluid flowthere-through, such as around the outer perimeter of the filter assembly550 and in a central opening of the filter assembly 550. An obstructioncan be formed through depositing an adhesive, such as a glue bead at therelevant location.

Each of the plurality of flutes 590 defines a flute distance between thefirst flow face 570 and the second flow face 580. In the currentembodiment, a first flute 594 of the plurality of flutes 590 defines afirst flute distance D₁ between the first flow face 570 and the secondflow face 580 and a second flute 596 of the plurality of flutes 590defines a second flute distance D₂ between the first flow face 570 andthe second flow face 580. In some examples, the first flute distance D₁is less than the second flute distance D₂, as currently depicted. Insome other examples, the first flute distance D₁ is greater than thesecond flute distance D₂. In certain embodiments, the first flutedistance D₁ and the second flute distance D₂ differ by greater than 2mm. In some embodiments, the first flute distance D₁ differs from thesecond flute distance D₂ by at least 5 mm, at least 8 mm or even atleast 15 mm. In some embodiments, the first flute distance D₁ differsfrom the second flute distance D₂ by 3 mm to 570 mm, 560 mm to 570 mm,or 15 mm to 25 mm.

In some embodiments, a third flute 598 of the plurality of flutes 590defines a third flute distance D₁ between the first flow face 570 andthe second flow face 580. The third flute distance D₁ will generallydiffer from at least one of the first flute distance D₁ and the secondflute distance D₂ by greater than 2 mm. In some embodiments the thirdflute distance D₁ differs from both the first flute distance D₁ and thesecond flute distance D₂ by greater than 2 mm. The third flute distanceD₁ can differ from one or both the first flute distance D₁ and thesecond flute distance D₂ by similar ranges described above. In thecurrent example, the third flute distance D₁ is greater than the firstflute distance D₁ and the second flute distance D₂. In some otherexamples, the third flute distance D₁ is greater than one of the firstflute distance D₁ and the second flute distance D₂, and less than theother of the first flute distance D₁ and the second flute distance D₂,as will be appreciated.

The differences in flute distances between the first flow face 570 ofthe filter assembly 550 and the second flow face 580 of the filterassembly 550 is also evidenced by the shapes of the flow faces relativeto each other. In various embodiments, at least one of the first flowface 570 and the second flow face 580 is non-planar. In variousembodiments, at least one of the first flow face 570 and the second flowface 580 is substantially planar. In examples consistent with thisparticular embodiment, the first flow face 570 is non-planar and thesecond flow face 580 is planar. Further, in this particular embodiment,the first flow face 570 has a stepped configuration where the first flowface 570 defines multiple planes 576. Each plane can be offset fromother planes forming the first flow face 570 in the axial direction Z.The general shape of the first flow face 520 can be radially symmetricalrelative to the Z-axis, although in some embodiments the general shapeof the first flow face is asymmetrical to the Z-axis.

It will be appreciated that, in some alternative embodiments, the firstflow face 570 can be planar and the second flow face 580 can benon-planar. In some embodiments at least one flute in the plurality offlutes 590 defines a flute opening that is non-planar.

In examples consistent with the current embodiment, an obstruction 599is disposed adjacent to the fourth edge 567 of the second sheet offilter media 564 along the length of the second sheet of filter media564. As the fourth edge 567 of the second sheet of filter media 564 isgenerally planar when the filter media 560 is in a coiled configuration,the obstruction 599 also is generally planar when the filter media 560is in a coiled configuration.

Similar to the previous two examples, FIG. 16A depicts one examplefilter assembly 1800 consistent with the technology disclosed herein,where the filter assembly 1800 is coiled filter media 1810, and FIG. 16Bdepicts a facing view of the filter media 1810 in an uncoiledarrangement. The filter assembly 1800 is constructed of filter media1810 defining a first flow face 1820, a second flow face 1830, and aplurality of flutes 1840 extending from the first flow face 1820 to thesecond flow face 1830. In the current example, the first flow face 1820is defined on a first end 1802 of the filter assembly 1800 and thesecond flow face 1830 is defined on a second, opposite end 1804 of thefilter assembly 1800. The first flow face 1820 has an axial flow facelength L and the first flow face 1820 defines a taper for at least aportion of the axial flow face length L. In the current example, thetaper of the first flow face 1820 increases for at least a portion ofthe axial flow face length L.

The filter media 1810 is a plurality of sheets of filter media,specifically a first sheet of filter media 1812 and a second sheet offilter media 1814. The second sheet of filter media 1814 is visible inFIG. 16B, which is a portion of the filter media 1810 in a planar,uncoiled arrangement. FIG. 16B is a facing view of the second sheet offilter media 1814. The second sheet of filter media 1814 is adjacent tothe first sheet of filter media 1812. The first sheet of filter media1812 and the second sheet of filter media 1814 mutually define theplurality of flutes 1840. The filter media 1810 can have a variety ofconfigurations, some examples of which are described in association withFIGS. 6a-6d , and also described below.

The filter media 1810 defines a coiled configuration about a Z-axis.Accordingly, each of the first sheet of filter media 1812 and the secondsheet of filter media 1814 defines a coiled configuration around theZ-axis. As such, the plurality of flutes 1840 are also in a coiledconfiguration about the Z-axis. In the current embodiment the pluralityof flutes are parallel, but in some other embodiments the plurality offlutes are not parallel.

As visible in FIG. 16B, the filter media 1810 (particularly the firstsheet of filter media 1812 and the second sheet of filter media 1814)are generally elongate, which enables the first sheet of filter media1812 and the second sheet of filter media 1814 to be coiled about theZ-axis to form a filter assembly. In this example, the first sheet offilter media 1812 and the second sheet of filter media 1814 can bediscontinuous. In such embodiments, the first sheet of filter media 1812defines a first edge 1811 and a second edge 1813 (FIG. 16A) and thesecond sheet of filter media 1814 defines a third edge 1815 and a fourthedge 1817 (FIG. 16B). The first edge 1811 and the third edge 1815mutually define the first flow face 1820 of the filter assembly 1800.The second edge 1813 and the fourth edge 1817 mutually define the secondflow face 1830 of the filter assembly 1800. The first edge 1811 andthird edge 1815 mutually and individually form a curved line, which hasconvex and concave portions. The second edge 1813 and the fourth edge1817 mutually and individually form a straight line.

The filter media 1810 in examples consistent with the current embodimenthas four edges: a first elongate edge 1805 (corresponding to the firstedge 1811 and the third edge 1815), a second elongate edge 1807(corresponding to the second edge 1813 and the fourth edge 1817), afirst terminal edge 1808, and a second terminal edge 1809. The shape ofthe filter media 1810 is generally non-rectangular and non-trapezoidalat least based on the curve defined by the first elongate edge 1805.

The filter assembly 1800 is generally constructed to define a fluidpathway 1806 between the first flow face 1820 and the second flow face1830 through the filter media 1810 such that the fluid is filtered bythe filter media 1810. In particular, the plurality of flutes 1840defines either inlet flutes, or outlet flutes, similar to as-describedin FIG. 3.

Each of the plurality of flutes 1840 defines a flute opening 1842 and aflute closure (not visible). The flute opening 1842 forms an end-mostportion of the fluid pathway 1806 along the flutes to accommodate fluidflow into or out of the filter assembly 1800. The flute closureobstructs fluid flow along the flute, thereby defining a portion of thefluid pathway 1806 through the filter media 1810. So, for example, aplurality of inlet flutes can define the flute opening 1842 at the firstflow face 1820 and a flute closure is defined across the plurality ofinlet flutes towards the second flow face 1830. In some embodiments, theflute closure is adjacent to the second flow face 1830. Moreparticularly, the flute closure can abut the second flow face 1830. Theflute closure can be similar to flute closures discussed above.

In the current embodiment, the volume defined between an outer surface1816 of the first sheet of filter media 1812 (FIG. 16A) and an outersurface 1818 of the second sheet of filter media 1814 (FIG. 16B) whenthe filter media is coiled (FIG. 16A) defines a fluid pathway 1806 thatis not necessarily characterized as being defined by a plurality offlutes.

An obstruction can be disposed within the coil and outside of theplurality of flutes 1840 such that fluids passing through the first flowface 1820 and second flow face 1830 of the filter assembly 1800 mustfirst pass through the filter media 1810. Additional obstructions canalso be disposed in any other gaps in the filter media to prevent fluidflow there-through, such as around the outer perimeter of the filterassembly 1800 and in a central opening of the filter assembly 1800. Anobstruction can be formed through depositing an adhesive, such as a gluebead at the relevant location.

Each of the plurality of flutes 1840 defines a flute distance betweenthe first flow face 1820 and the second flow face 1830. In the currentembodiment, a first flute 1844 of the plurality of flutes 1840 defines afirst flute distance D₁ between the first flow face 1820 and the secondflow face 1830 and a second flute 1846 of the plurality of flutes 1840defines a second flute distance D₂ between the first flow face 1820 andthe second flow face 1830. In some examples, the first flute distance D₁is less than the second flute distance D₂, as currently depicted. Insome other examples, the first flute distance D₁ is greater than thesecond flute distance D₂. In certain embodiments, the first flutedistance D₁ and the second flute distance D₂ differ by greater than 2mm. In some embodiments, the first flute distance D₁ differs from thesecond flute distance D₂ by at least 10 mm, at least 8 mm or even atleast 15 mm. In some embodiments, the first flute distance D₁ differsfrom the second flute distance D₂ by 3 mm to 1020 mm, 1010 mm to 1020mm, or 15 mm to 25 mm.

In some embodiments, a third flute 1848 of the plurality of flutes 1840defines a third flute distance D₁ between the first flow face 1820 andthe second flow face 1830. The third flute distance D₁ will generallydiffer from at least one of the first flute distance D₁ and the secondflute distance D₂ by greater than 2 mm. In some embodiments the thirdflute distance D₁ differs from both the first flute distance D₁ and thesecond flute distance D₂ by greater than 2 mm. The third flute distanceD₁ can differ from one or both the first flute distance D₁ and thesecond flute distance D₂ by similar ranges described above. In thecurrent example, the third flute distance D₁ is greater than the firstflute distance D₁ and the second flute distance D₂. In some otherexamples, the third flute distance D₁ is greater than one of the firstflute distance D₁ and the second flute distance D₂, and less than theother of the first flute distance D₁ and the second flute distance D₂,as will be appreciated.

The differences in flute distances between the first flow face 1820 ofthe filter assembly 1800 and the second flow face 1830 of the filterassembly 1800 is also evidenced by the shapes of the flow faces relativeto each other. In various embodiments, at least one of the first flowface 1820 and the second flow face 1830 is non-planar. In variousembodiments, at least one of the first flow face 1820 and the secondflow face 1830 is substantially planar. In examples consistent with thisparticular embodiment, the first flow face 1820 is non-planar and thesecond flow face 1830 is planar. Further, in this particular embodiment,the first flow face 1820 is configured such that it protrudes outwardfrom the filter assembly in the axial direction Z. The general shape ofthe first flow face 1820 can be considered radially symmetrical relativeto the Z-axis.

It will be appreciated that, in some alternative embodiments, the firstflow face 1820 can be planar and the second flow face 1830 can benon-planar. In some embodiments at least one flute in the plurality offlutes 1840 defines a flute opening that is non-planar.

In examples consistent with the current embodiment, an obstruction 1849is disposed adjacent to the fourth edge 1817 of the second sheet offilter media 1814 along the length of the second sheet of filter media1814. As the fourth edge 1817 of the second sheet of filter media 1814is generally planar when the filter media 1810 is in a coiledconfiguration, the obstruction 1849 also is generally planar when thefilter media 1810 is in a coiled configuration.

FIG. 17A depicts yet another example filter assembly 1100 consistentwith the technology disclosed herein, where the filter assembly 1100 iscoiled filter media 1110, and FIG. 17B depicts a facing view of thefilter media 1110 in an uncoiled arrangement. The filter assembly 1100is constructed of filter media 1110 defining a first flow face 1120, asecond flow face 1130, and a plurality of flutes 1140 extending from thefirst flow face 1120 to the second flow face 1130. In the currentexample, the first flow face 1120 is defined on a first end 1102 of thefilter assembly 1100 and the second flow face 1130 is defined on asecond, opposite end 1104 of the filter assembly 1100. The first flowface 1110 has an axial flow face length L. In this example, the firstflow face 1120 does not define a taper along at least a portion of theaxial flow face length L.

The filter media 1110 is a plurality of sheets of filter media,specifically a first sheet of filter media 1112 and a second sheet offilter media 1114. The second sheet of filter media 1114 is visible inFIG. 17B, which is a portion of the filter media 1110 in a planararrangement. FIG. 17B is a facing view of the second sheet of filtermedia 1114. The second sheet of filter media 1114 is adjacent to thefirst sheet of filter media 1112. The first sheet of filter media 1112and the second sheet of filter media 1114 mutually define the pluralityof flutes 1140. The filter media 1110 can have a variety ofconfigurations, some examples of which are described in association withFIGS. 6a-6d , and also described below.

It is noted that the totality of the flutes that would be defined in anactual implementation of this design have been omitted from FIG. 17A tosimplify the drawing and provide clarity regarding the relativelycomplex shape of the first flow face 1120.

The filter media 1110 defines a coiled configuration about a Z-axis.Accordingly, each of the first sheet of filter media 1112 and the secondsheet of filter media 1114 defines a coiled configuration around theZ-axis. As such, the plurality of flutes 1140 are also in a coiledconfiguration about the Z-axis. In the current embodiment the pluralityof flutes are parallel, but in some other embodiments the plurality offlutes are not parallel.

As visible in FIG. 17B, the filter media 1110 (particularly the firstsheet of filter media 1112 and the second sheet of filter media 1114)are generally elongate, which enables the first sheet of filter media1112 and the second sheet of filter media 1114 to be coiled about theZ-axis to form a filter assembly. In this example, the first sheet offilter media 1112 and the second sheet of filter media 1114 arecontinuous or discontinuous. In embodiments where the sheets arediscontinuous, the first sheet of filter media 1112 defines a first edge1111 and a second edge 1113 (FIG. 17A), and the second sheet of filtermedia 1114 defines a third edge 1115 and a fourth edge 1117 (FIG. 17B).The first edge 1111 and the third edge 1115 mutually define the firstflow face 1120 of the filter assembly 1100. The second edge 1113 and thefourth edge 1117 mutually define the second flow face 1130 of the filterassembly 1100. The first edge 1111 and third edge 1115 each individuallyforms a sine wave pattern having a constant frequency across the lengthof the filter media 1110. The second edge 1113 and the fourth edge 1117each individually forms a straight line.

The filter media 1110 in examples consistent with the current embodimenthas four edges: a first elongate edge 1105 (corresponding to the firstedge 1111 and the third edge 1115), a second elongate edge 1107(corresponding to the second edge 1113 and the fourth edge 1117), afirst terminal edge 1108, and a second terminal edge 1109. The shape ofthe filter media 1110 is generally non-rectangular and non-trapezoidalat least based on the wave pattern defined by the first elongate edge,which defines a plurality of convex and concave portions.

The filter assembly 1100 is generally constructed to define a fluidpathway 1106 between the first flow face 1120 and the second flow face1130 through the filter media 1110 such that the fluid is filtered bythe filter media 1110. In particular, the plurality of flutes 1140defines either inlet flutes, or outlet flutes, similar to as-describedin FIG. 3.

Each of the plurality of flutes 1140 defines a flute opening 1142 and aflute closure (not visible). The flute opening 1142 forms an end-mostportion of the fluid pathway 1106 along the flutes to accommodate fluidflow into or out of the filter assembly 1100. The flute closureobstructs fluid flow along the flute, thereby defining a portion of thefluid pathway 1106 through the filter media 1110. So, for example, aplurality of inlet flutes can define the flute opening 1142 at the firstflow face 1120 and a flute closure is defined across the plurality ofinlet flutes towards the second flow face 1130. In some embodiments, theflute closure is adjacent to the second flow face 1130. Moreparticularly, the flute closure can abut the second flow face 1130. Theflute closure can be similar to flute closures discussed above.

In the current embodiment, the volume defined between an outer surface1116 of the first sheet of filter media 1112 (FIG. 17A) and an outersurface 1118 of the second sheet of filter media 1114 (FIG. 17B) whenthe filter media is coiled (FIG. 17A) defines a fluid pathway 1106 thatis not necessarily characterized as being defined by a plurality offlutes.

An obstruction can be disposed within the coil and outside of theplurality of flutes 1140 such that fluids passing through the first flowface 1120 and second flow face 1130 of the filter assembly 1100 mustfirst pass through the filter media 1110. Additional obstructions canalso be disposed in any other gaps in the filter media to prevent fluidflow there-through, such as around the outer perimeter of the filterassembly 1100 and in a central opening of the filter assembly 1100. Anobstruction can be formed through depositing an adhesive, such as a gluebead at the relevant location.

Each of the plurality of flutes 1140 defines a flute distance betweenthe first flow face 1120 and the second flow face 1130. In the currentembodiment, a first flute 1144 of the plurality of flutes 1140 defines afirst flute distance D₁ between the first flow face 1120 and the secondflow face 1130 and a second flute 1146 of the plurality of flutes 1140defines a second flute distance D₂ between the first flow face 1120 andthe second flow face 1130. In some examples, the first flute distance D₁is less than the second flute distance D₂, as currently depicted. Insome other examples, the first flute distance D₁ is greater than thesecond flute distance D₂. In certain embodiments, the first flutedistance D₁ and the second flute distance D₂ differ by greater than 2mm. In some embodiments, the first flute distance D₁ differs from thesecond flute distance D₂ by at least 5 mm, at least 8 mm or even atleast 15 mm. In some embodiments, the first flute distance D₁ differsfrom the second flute distance D₂ by 3 mm to 20 mm, 10 mm to 20 mm, or15 mm to 25 mm.

In some embodiments, a third flute 1148 of the plurality of flutes 1140defines a third flute distance D₁ between the first flow face 1120 andthe second flow face 1130. The third flute distance D₁ will generallydiffer from at least one of the first flute distance D₁ and the secondflute distance D₂ by greater than 2 mm. In some embodiments the thirdflute distance D₁ differs from both the first flute distance D₁ and thesecond flute distance D₂ by greater than 2 mm. The third flute distanceD₁ can differ from one or both the first flute distance D₁ and thesecond flute distance D₂ by similar ranges described above. In thecurrent example, the third flute distance D₁ is greater than the firstflute distance D₁ and the second flute distance D₂. In some otherexamples, the third flute distance D₁ is greater than one of the firstflute distance D₁ and the second flute distance D₂, and less than theother of the first flute distance D₁ and the second flute distance D₂,as will be appreciated.

The differences in flute distances between the first flow face 1120 ofthe filter assembly 1100 and the second flow face 1130 of the filterassembly 1100 is also evidenced by the shapes of the flow faces relativeto each other. In various embodiments, at least one of the first flowface 1120 and the second flow face 1130 is non-planar. In variousembodiments, at least one of the first flow face 1120 and the secondflow face 1130 is substantially planar. In examples consistent with thisparticular embodiment, the first flow face 1120 is non-planar and thesecond flow face 1130 is planar. Further, in this particular embodiment,the first flow face 1120 is configured such that the first elongate edgeof the filter media 1110 undulates circumferentially about the Z-axis.

It will be appreciated that, in some alternative embodiments, the firstflow face 1120 can be planar and the second flow face 1130 can benon-planar. In some embodiments at least one flute in the plurality offlutes 1140 defines a flute opening that is non-planar.

In examples consistent with the current embodiment, an obstruction 1149is disposed adjacent to the fourth edge 1117 of the second sheet offilter media 1114 along the length of the second sheet of filter media1114. As the fourth edge 1117 of the second sheet of filter media 1114is generally planar when the filter media 1110 is in a coiledconfiguration, the obstruction 1149 also is generally planar when thefilter media 1110 is in a coiled configuration.

FIG. 18 depicts a side cut-away view of yet another example filterassembly 1200 consistent with the technology disclosed herein. Thefilter assembly 1200 is constructed of filter media 1210 having a firstelongate edge 1212 defining a first flow face 1220, a second elongateedge 1214 defining a second flow face 1230, and a plurality of flutes1240 extending from the first flow face 1220 to the second flow face1230. In the current example, the first flow face 1220 is defined on afirst end 1202 of the filter assembly 1200 and the second flow face 1230is defined on a second, opposite end 1204 of the filter assembly 1200.The first flow face 1220 has a first axial flow face length L₁ and thesecond flow face 1230 has a second axial flow face length L₂. Each ofthe first flow face 1220 and the second flow face 1230 defines a taperalong the respective axial flow face length.

Similar to other embodiments described herein, the filter assembly 1200is generally constructed to define a fluid pathway 1218 between thefirst flow face 1220 and the second flow face 1230 through the filtermedia 1210 such that the fluid is filtered by the filter media 1210. Inthis example, each of the plurality of flutes 1240 defines a fluteopening and a flute closure, as described with reference to previousfigures. Also similar to some other embodiments, the filter assembly1200 is constructed of filter media 1210 that is in a coiledconfiguration about a Z-axis. The first sheet of filter media 1250 andthe second sheet of filter media 1260 mutually define the plurality offlutes 1240. The filter media 1210 has a first sheet of filter media1250 that is fluted and a second sheet of filter media 1260 that is afacing sheet adjacent to the first sheet of filter media 1250. Thefilter assembly 1200 of FIG. 18 can be constructed from variety ofconfigurations of filter media 1210, examples of which are described inassociation with FIGS. 6a-6d , and also as-described below.

The first sheet of filter media 1250 and the second sheet of filtermedia 1260 are generally elongate. In this example, the first sheet offilter media 1250 and the second sheet of filter media 1260 arediscontinuous. The first sheet of filter media 1250 defines a first edge1253 and the second sheet of filter media 1260 defines a second edge1263. The first edge 1253 and the second edge 1263 are configured tomutually define the first flow face 1220, and therefore the firstelongate edge 1212, of the filter assembly 1200. The first sheet offilter media 1250 defines a third edge 1255 and the second sheet offilter media 1260 defines a fourth edge 1265. The third edge 1255 andthe fourth edge 1265 are configured to mutually define the second flowface 1230, and therefore the second elongate edge 1214, of the filterassembly 1200.

Each of the first sheet of filter media 1250 and the second sheet offilter media 1260 are arranged to define a coiled configuration aboutthe Z-axis. As such, the plurality of flutes 1240 are also in a coiledconfiguration about the Z-axis. In this example, the plurality of flutes1240 are generally parallel.

Each of the plurality of flutes 1240 defines a flute distance betweenthe first flow face 1220 and the second flow face 1230. In the currentembodiment, a first flute 1244 of the plurality of flutes 1240 defines afirst flute distance D₁ between the first flow face 1220 and the secondflow face 1230 and a second flute 1246 of the plurality of flutes 1240defines a second flute distance D₂ between the first flow face 1220 andthe second flow face 1230. In the current embodiment the first flutedistance D₁ is less than the second flute distance D₂, but in otherembodiments the first flute distance D₁ is greater than the second flutedistance D₂. In a variety of embodiments, the first flute distance D₁and the second flute distance D₂ differ by greater than 2 mm. In someembodiments, the first flute distance D₁ differs from the second flutedistance D₂ by at least 5 mm, at least 8 mm or even at least 15 mm. Insome embodiments, the first flute distance D₁ differs from the secondflute distance D₂ by 3 mm to 20 mm, 10 mm to 20 mm, or 15 mm to 25 mm.

In some embodiments, a third flute 1248 of the plurality of flutes 1240defines a third flute distance D₁ between the first flow face 1220 andthe second flow face 1230. In the current embodiment the third flutedistance D₁ is greater than the first flute distance D₁ and the secondflute distance D₂, but flute distances can have other relativerelationships, as has been described above. The third flute distance D₁will generally differ from at least one of the first flute distance D₁and the second flute distance D₂ by greater than 2 mm. In someembodiments the third flute distance D₁ differs from both the firstflute distance D₁ and the second flute distance D₂ by greater than 2 mm.The third flute distance D₁ can differ from one or both the first flutedistance D₁ and the second flute distance D₂ by similar ranges describedabove.

In examples consistent with this particular embodiment, the first flowface 1220 is non-planar and the second flow face 1230 is non-planar. Oneor both of the first flow face and the second flow face can be cut to bea three-dimensional surface. In the current example, at least one of thefirst flow face 1220 and the second flow face 1230 is recessed and, assuch, defines a void that projects inward relative to the filterassembly 1200. In the current example, the first flow face 1220 and thesecond flow face 1230 each define a depression and are each recessed. Insome other embodiments, one of the first flow face 1220 and the secondflow face 1230 is recessed relative to the filter assembly, and theother of the first flow face 1220 and the second flow face 1230 isplanar or protrudes. In the current example, the general shape of thefirst flow face 1220 and the second flow face 1230 are symmetricalrelative to the Z-axis. In some other embodiments, the first flow face1220 and the second flow face 1230 are asymmetrical relative to theZ-axis. In some embodiments the first flow face 1220 and the second flowface 1230 have similar shapes, and in other embodiments the first flowface 1220 and the second flow face 1230 have dissimilar shapes.

FIG. 19 depicts a side cut-away view of yet another example filterassembly 1300 consistent with the technology disclosed herein. Thefilter assembly 1300 is constructed of filter media 1310 having a firstelongate edge 1312 defining a first flow face 1320, a second elongateedge 1314 defining a second flow face 1330, and a plurality of flutes1340 extending from the first flow face 1320 to the second flow face1330. In the current example, the first flow face 1320 is defined on afirst end 1302 of the filter assembly 1300 and the second flow face 1330is defined on a second, opposite end 1304 of the filter assembly 1300.The first flow face 1320 has a first axial flow face length L₁ and thesecond flow face 1330 has a second axial flow face length L₂. Each ofthe first flow face 1320 and the second flow face 1330 defines a taperalong the respective axial flow face length.

Similar to other embodiments described herein, the filter assembly 1300is generally constructed to define a fluid pathway 1318 between thefirst flow face 1320 and the second flow face 1330 through the filtermedia 1310 such that the fluid is filtered by the filter media 1310. Assuch, each of the plurality of flutes 1340 defines a flute opening and aflute closure, as described with reference to previous figures. Alsosimilar to some other embodiments, the filter assembly 1300 isconstructed of filter media 1310 that is in a coiled configuration abouta Z-axis. The filter media 1310 has a first sheet of filter media thatis fluted and a second sheet of filter media adjacent to the first sheetof filter media (not currently distinguishable from this view). Thefirst sheet of filter media and the second sheet of filter mediamutually define the plurality of flutes. The filter assembly 1300 ofFIG. 19 can be constructed from variety of alternate configurations offilter media 1310, examples of which are described in association withFIGS. 6a-6d , and also as described below.

Each of the first sheet of filter media and the second sheet of filtermedia are arranged to define a coiled configuration about the Z-axis. Assuch, the plurality of flutes are also in a coiled configuration aboutthe Z-axis. In this example, the plurality of flutes 1340 are generallyparallel.

Each of the plurality of flutes 1340 defines a flute distance betweenthe first flow face 1320 and the second flow face 1330. In the currentembodiment, a first flute 1344 of the plurality of flutes 1340 defines afirst flute distance D₁ between the first flow face 1320 and the secondflow face 1330 and a second flute 1346 of the plurality of flutes 1340defines a second flute distance D₂ between the first flow face 1320 andthe second flow face 1330. In the current embodiment the first flutedistance D₁ is less than the second flute distance D₂, but in otherembodiments the first flute distance D₁ is greater than the second flutedistance D₂. In a variety of embodiments, the first flute distance D₁and the second flute distance D₂ differ by greater than 13 mm. In someembodiments, the first flute distance D₁ differs from the second flutedistance D₂ by at least 5 mm, at least 8 mm or even at least 15 mm. Insome embodiments, the first flute distance D₁ differs from the secondflute distance D₂ by 3 mm to 20 mm, 10 mm to 20 mm, or 15 mm to 25 mm.

In some embodiments, a third flute 1348 of the plurality of flutes 1340defines a third flute distance D₁ between the first flow face 1320 andthe second flow face 1330. In the current embodiment the third flutedistance D₁ is greater than the first flute distance D₁ and the secondflute distance D₂, but flute distances can have other relativerelationships, as has been described above. The third flute distance D₁will generally differ from at least one of the first flute distance D₁and the second flute distance D₂ by greater than 2 mm. In someembodiments the third flute distance D₁ differs from both the firstflute distance D₁ and the second flute distance D₂ by greater than 2 mm.The third flute distance D₁ can differ from one or both the first flutedistance D₁ and the second flute distance D₂ by similar ranges describedabove.

In various embodiments, at least one of the first flow face 1320 and thesecond flow face 1330 is planar. In examples consistent with thisparticular embodiment, the first flow face 1320 is planar and the secondflow face 1330 is planar, and the first flow face 1320 is non-paralleland non-perpendicular to the second flow face 1330. Unlike the exampleof FIG. 5, here each of the flow faces are not perpendicular to theflutes.

FIG. 20 depicts a side cut-away view of yet another example filterassembly 1400 consistent with the technology disclosed herein. Thefilter assembly 1400 is constructed of filter media 1410 having a firstelongate edge 1412 defining a first flow face 1420, a second elongateedge 1414 defining a second flow face 1430, and a plurality of flutes1440 extending from the first flow face 1420 to the second flow face1430. In the current example, the first flow face 1420 is defined on afirst end 1402 of the filter assembly 1400 and the second flow face 1430is defined on a second, opposite end 1404 of the filter assembly 1400.The first flow face 1420 has a first axial flow face length L₁ and thesecond flow face 1430 has a second axial flow face length L₂. Each ofthe first flow face 1420 and the second flow face 1430 defines a taperalong its respective axial flow face length.

Similar to other embodiments described herein, the filter assembly 1400is generally constructed to define a fluid pathway 1418 between thefirst flow face 1420 and the second flow face 1430 through the filtermedia 1410 such that the fluid is filtered by the filter media 1410. Assuch, each of the plurality of flutes 1440 defines a flute opening and aflute closure, as described with reference to previous figures. Alsosimilar to some other embodiments, the filter assembly 1400 isconstructed of filter media 1410 that is in a coiled configuration abouta Z-axis. The filter media 1410 has a first sheet of filter media thatis fluted and a second sheet of filter media adjacent to the first sheetof filter media (not discernable in this view). The first sheet offilter media and the second sheet of filter media can be consistent withexamples described in association with FIGS. 6a-6d , and also examplesas-described below.

Each of the first sheet of filter media and the second sheet of filtermedia are arranged to define a coiled configuration about the Z-axis. Assuch, the plurality of flutes 1440 are also in a coiled configurationabout the Z-axis. In this example, the plurality of flutes 1440 aregenerally parallel.

Each of the plurality of flutes 1440 defines a flute distance betweenthe first flow face 1420 and the second flow face 1430. In the currentembodiment, a first flute 1444 of the plurality of flutes 1440 defines afirst flute distance D₁ between the first flow face 1420 and the secondflow face 1430 and a second flute 1446 of the plurality of flutes 1440defines a second flute distance D₂ between the first flow face 1420 andthe second flow face 1430. In the current embodiment the first flutedistance D₁ is less than the second flute distance D₂, but in otherembodiments the first flute distance D₁ is greater than the second flutedistance D₂. In a variety of embodiments, the first flute distance D₁and the second flute distance D₂ differ by greater than 2 mm. In someembodiments, the first flute distance D₁ differs from the second flutedistance D₂ by at least 5 mm, at least 8 mm or even at least 15 mm. Insome embodiments, the first flute distance D₁ differs from the secondflute distance D₂ by 3 mm to 20 mm, 10 mm to 20 mm, or 15 mm to 25 mm.

In some embodiments, a third flute 1448 of the plurality of flutes 1440defines a third flute distance D₁ between the first flow face 1420 andthe second flow face 1430. In the current embodiment the third flutedistance D₁ is greater than the first flute distance D₁ and the secondflute distance D₂, but flute distances can have other relativerelationships, as has been described above. The third flute distance D₁will generally differ from at least one of the first flute distance D₁and the second flute distance D₂ by greater than 2 mm. In someembodiments the third flute distance D₁ differs from both the firstflute distance D₁ and the second flute distance D₂ by greater than 2 mm.The third flute distance D₁ can differ from one or both the first flutedistance D₁ and the second flute distance D₂ by similar ranges describedabove.

In examples consistent with this particular embodiment, the first flowface 1420 is non-planar and the second flow face 1430 is non-planar. Oneor both of the first flow face and the second flow face can be cut to bea three-dimensional surface. In the current example, at least one of thefirst flow face 1420 and the second flow face 1430 protrudes relative tothe filter assembly 1400. In the current example, the first flow face1420 and the second flow face 1430 each protrude axially outward fromthe filter assembly 1400 (in the Z-direction). In some alternateembodiments, at least one of the first flow face 1420 and the secondflow face 1430 protrudes outward and the other of the first flow face1420 and the second flow face 1430 is recessed or is planar.

Additional Media Configurations

The filter assemblies described herein can be constructed of filtermedia having a variety of different configurations, including thosealready depicted herein. Various embodiments, including in any of theexample filter assemblies disclosed herein, can incorporate filter mediaconstructed of a fluted sheet and a facing sheet adjacent to the flutedsheet, where a plurality of flutes is defined that extend between thefluted sheet and facing sheet. In some of those embodiments, the flutedsheet defines a plurality of protrusions that contact the facing sheet.Example filter medias are described, for example, in U.S. Pat. No.9,623,362, which is incorporated by reference herein.

Also, in some of those embodiments, the fluted sheet defines a ridgealong at least a portion of the length of a portion of the flutes, wherea ridge is a line of intersection between differently-sloped portions ofmedia forming the particular flute. Also, in some of those embodiments,at least a portion of the flutes can define flute peaks that are sharp,meaning the flute peak is not curved. Also, in some of thoseembodiments, at least a portion of the flutes can be tapered from afirst flow face of the media assembly to the second flow face of themedia assembly. The above and other flute configuration are certainlycontemplated, such as disclosed in U.S. Pat. Nos. 7,959,702 and8,545,589, which are each incorporated by reference herein. In someembodiments, flutes do not extend from a first flow face to a secondflow face of the filter media, such as where a portion of the flutestaper to a point between the first flow face and second flow face of thefilter media.

Filter assemblies constructed of fluted media consistent with thetechnology disclosed herein can incorporate different types of filtermedia arranged in parallel or in a series, where “different types offilter media” is used to mean that the filter media is constructed ofdifferent materials, or has flutes that exhibit differences in fluteshape, flute size, flute height, flute width, flute length, cross-flutearea, and/or filter media. Such configurations are described in PCT Pub.No. WO 2008/111923 and U.S. Pat. App. No. 62/683,542, which areincorporated herein by reference.

In some embodiments, where the filter media is constructed of a flutedsheet and a facing sheet that mutually defines a plurality of flutes,the plurality of flutes has at least a first group of flutes and asecond group of flutes, where the first and second group of flutesexhibit differences in flute shape, flute size, flute height, flutewidth, flute length, cross-flute area, and/or filter media.

FIG. 21 depicts a cross-sectional view of an example filter media 1500consistent with various embodiments. A first sheet of filter media 1502and a second sheet of filter media 1504 mutually define a plurality offlutes 1506. The filter assembly 1500 has two types of flutes: firstflutes 1510, and second flutes 1520. The first flutes 1510 and secondflutes 1520 are arranged in parallel flow. The filter media 1500 can beused to form coiled filter assemblies (as has been described), or thefilter media 1500 can be stacked with similar or different filter mediato form panel filter assemblies consistent with embodiments herein. Inexample constructions having two types of flutes, as currently depicted,the first and second flutes can be selected such that the firstplurality of flutes comprises 20 to 50 percent of the volume of thefilter assembly, such as 20, 30, 40, or 50 percent the volume of filterassembly; the second plurality of flutes comprises 20 to 50 percent thevolume of the pack, such as 20, 30, 40 or 50 percent of the volume offilter assembly.

In an example construction having two types of flutes, the first andsecond flutes can be selected such that the first plurality of flutescomprises 20 to 50 percent of the media surface area of the filterassembly, such as 20, 30, 40, or 50 percent of the media surface area ofthe filter assembly; and the second plurality of flutes comprises 20 to50 percent of the media surface area of the filter assembly, such as 20,30, 40 or 50 percent of the media surface area of the filter assembly.

In an example construction having two types of flutes, the first andsecond flutes can be selected such that the first plurality of flutescomprises 20 to 50 percent of the inlet face of the filter assembly,such as 20, 30, 40, or 50 percent of the inlet face of the filterassembly; and the second plurality of flutes comprises 20 to 50 percentof the inlet face of the filter assembly, such as 20, 30, 40 or 50percent of the inlet face of the filter assembly.

While FIG. 21 depicts two different types of flutes, other embodimentscan have additional different types of flutes incorporated in the filtermedia.

Filter assemblies having a stacked configuration as described herein canbe constructed of multiple different types of filter media in the stack.FIG. 22 is a facing schematic view of an example filter assembly 1600,showing a stacked configuration with two types of filter media. The twotypes of filter media are first media 1610 and a second media 1620. Thefilter media are arranged in parallel with respect to fluid flow. Themedia is shown in a stacked configuration with the two types of filtermedia being segregated by media type rather than intermixed. In thisexample embodiment the ratio of filter media 1610 to 820 to 830 isapproximately 4:3, based upon filter assembly inlet (or outlet) area.

In some implementations the first media (having a first plurality offlutes) defines from 10 to 90 percent of the inlet face of the mediaassembly, such as 10, 20, 30, 40, 50, 60, 70, 80 or 90 percent of theinlet face of the filter assembly; and the second filter assembly(having a second plurality of flutes) defines from 90 to 10 percent ofthe inlet face of the media assembly, such as 90, 80, 70, 60, 50, 40,30, 20 or 10 percent of the inlet face of the media assembly.Alternatively, the first plurality of flutes comprises from 20 to 40percent of the inlet face of the media assembly, and the secondplurality of flutes comprises from 60 to 80 percent of the inlet face ofthe media assembly. In other implementations the first plurality offlutes comprises from 40 to 60 percent of the inlet face of the mediaassembly, and the second plurality of flutes comprises from 60 to 40percent of the inlet face of the media assembly. In yet anotherimplementation the first plurality of flutes comprises from 60 to 90percent of the inlet face of the media assembly, and the secondplurality of flutes comprises from 40 to 10 percent of the inlet face ofthe media assembly.

Media assemblies having a coiled media arrangement consistent with thepresent disclosure can also be constructed of multiple types of filtermedia arranged in a series. FIG. 23 is a schematic cross-sectional viewof an example filter assembly 1700, showing a wound configuration withtwo types of filter media 1710 and 1720. The media is coiled with thefirst media 1710 on the inside and the second media 1720 on the outside.The first and second medias 1710, 1720 are spliced together. While theflutes are not currently depicted, it should be understood that each ofthe first and second media is generally fluted media. The first 1710 andsecond 1720 medias can have ratios and parameters consistent with thatdescribed above with reference to FIG. 22.

FIG. 24 is a cross-sectional view of a two-stage separator system 2000consistent with FIG. 1. Unlike FIG. 2, the current cross section istaken through the filter assembly as well as the separator housing, sothat an alternate filter assembly configuration is visible. Theseparator system 2000 has a housing 2010 that houses a filter assembly2050 disposed therein. The filter assembly 2050 can be generallyconsistent with filter assemblies described herein above.

The housing 2010 extends between a first end 2012 and a second end 2014.The housing 2010 defines an interior volume 2016. In various embodimentsthe housing 2010 extends in an axial direction defined by a central axisz. The housing 2010 defines a housing inlet 2020, a separator outlet2030 towards the second end 2014, and a filtration outlet 2040 on thefirst end 2012. In this example, the housing inlet 2020 is definedtowards the first end 2012. A filter assembly 2050 is positioned in theinterior volume 2016. The housing 2010 is configured to receiveunfiltered fluid, such as air, through the housing inlet 2020, allowexpulsion of separated particulates through the separator outlet 2030,and allow filtered air to exit through filtration outlet 2040. Thisfunctionality similar to the description above with respect to FIGS. 1and 2.

The housing 2010 has a main portion 2060 and an access cover 2070 thatare detachably coupled. The main portion 2060 can define the first end2012 of the housing 2010 and the access cover 2070 can define the secondend 2014 of the housing 2010. The main portion 2060 and the access cover2070 are detachably coupled as described above with reference to FIGS. 1and 2. The access cover 2070 encloses the second end 2062 of the mainportion 2060 of the housing 2010.

The specific configurations of the housing inlet 2020, separator outlet2030, and filtration outlet 2040 can be similar to that described abovewith reference to FIGS. 1 and 2.

A filter assembly 2050 is disposed in the housing 2010, that isgenerally configured to filter air within the housing 2010. The filterassembly 2050 has an inlet flow face 2052, an outlet flow face 2054, andfilter media 2056 extending in the axial direction between the inletflow face 2052 and the outlet flow face 2054. While not visible in thecurrent view, the filter media 2056 defines a plurality of flutesextending in the axial direction. The flutes can extend between theinlet flow face 2052 and the outlet flow face 2054 in the axialdirection. The filter assembly 2050 is similar to the filter assemblydepicted and discussed with respect to FIG. 18, in that each flow face2052, 2054 has an axial length L₁, L₂, respectively. In particular, theinlet flow face 2052 and the outlet flow face 2054 is recessed andextends inward relative to the filter assembly 2050.

The filter assembly 2050 is coupled to the housing 2010 about thefiltration outlet 2040 such that the outlet flow face 2054 is in fluidcommunication with the filtration outlet 2040. In various embodiments,the filter media 2056 surrounding the outlet flow face 2054 is coupledto the housing 2010 about the filtration outlet 2040. In the currentexample, the filter assembly 2050 has a a potting feature 2026 that is aradial potting sleeve configured to receive a first end of the filtermedia 2056. The first end 2051 of the filter assembly 2050 can becoupled to the housing 2010 using adhesives, gaskets, compression fits,and/or through additional or alternative structures.

The filter assembly 2050 has an outer radial barrier surface 2058between the inlet flow face 2052 and the outlet flow face 2054. In someembodiments, the outer radial barrier surface 2058 can be configured toguide airflow tangentially about the filter assembly 2050. The outerradial barrier surface 2058 can have a configuration consistent with thedescription above with respect to FIG. 2. The outer radial barriersurface 2058 has a length Lsurface extending in the axial direction,which is greater than or equal to an axial distance D from thefiltration outlet 2040 to a distal end of the housing inlet 2020. Insome embodiments, the outer radial barrier surface 2058 extends axiallyfrom the filtration outlet 2040 beyond the housing inlet 2020. Such aconfiguration encourages spiraling airflow about the filter assembly2050 towards the second end 2014 of the housing 2010.

The inlet flow face 2052 of the filter assembly 2050 has a flow facelength L₁ in the axial direction z. Unlike the example of FIG. 2, herethe inlet flow face 2052 defines a taper for at least a portion of theaxial flow face length L_(inlet) from the second end 2014 towards thefirst end 2012 of the housing 2010. In some embodiments where the inletflow face 2052 defines a taper for at least a portion of the axial flowface length L_(inlet), the taper increases for at least a portion of theaxial flow face length L_(inlet) from the second end 2014 towards thefirst end 2012. The taper of the inlet flow face 2052 continuouslychanges along the axial flow face length L_(inlet) from the first end2012 towards the second end 2014. Indeed, in the current example, thetaper of the inlet flow face 2052 continuously increases along the axialflow face length L_(inlet) from the second end 2014 towards the firstend 2012.

A radial distance R_(1,2) is generally defined between the inlet flowface 2052 and the housing 2010. In various embodiments, the radialdistance R_(1,2) increases for at least a portion of the axial flow facelength L_(inlet) from the second end 2014 towards the first end 2012 ofthe housing 2010, as demonstrated by a first radial distance R₁ and asecond radial distance R₂. Similar to the discussion above with respectto FIG. 2, while the housing 2010 is not shown as tapering here, in someexamples the housing can define a taper along at least a portion of theaxial length of the housing 2010.

In the embodiment depicted, the filter media 2056 is at least a firstsheet of filter media and a second sheet of filter media in a coiledconfiguration about the z-axis, similar to the filter assembly describedabove with respect to FIG. 18.

DESCRIPTION OF EXEMPLARY EMBODIMENTS OF A TWO-STAGE SEPARATOR SYSTEM OFTHE CURRENT TECHNOLOGY Embodiment 1

A two-stage separator system comprising:

-   a housing extending between a first end and a second end, the    housing defining a housing inlet, a separator outlet towards the    second end, and a filtration outlet on the first end; and a filter    assembly having a first sheet of filter media coupled to a second    sheet of filter media mutually defining a plurality of flutes    extending in an axial direction, wherein the filter assembly defines    an inlet flow face and an outlet flow face,-   wherein the filter assembly is disposed in the housing and coupled    to the housing about the filtration outlet such that the outlet flow    face is in fluid communication with the filtration outlet, and-   wherein the inlet flow face has an axial flow face length.

Embodiment 2

The system of any one of claims 1 and 3-17, wherein a radial distance isdefined between the inlet flow face and the housing, wherein the radialdistance increases for at least a portion of the axial flow face lengthfrom the first end towards the second end.

Embodiment 3

The system of any one of embodiments 1-2 and 4-17, wherein the filterassembly has an outer radial barrier surface extending axially from thefiltration outlet beyond the housing inlet.

Embodiment 4

The system of any one of embodiments 1-3 and 5-17, wherein the filterassembly has an outer radial barrier surface having an axial length fromthe outlet flow face towards the inlet flow face that is greater than orequal to an axial distance from the filtration outlet to a distal end ofthe housing inlet.

Embodiment 5

The system of any one of embodiments 1-4 and 6-17, wherein the housinginlet defines an airflow pathway that is tangential to an outer radialbarrier surface of the filter assembly.

Embodiment 6

The system of any one of embodiments 1-5 and 7-17, wherein at least aportion of the outer radial barrier surface is defined by the firstsheet of filter media.

Embodiment 7

The system of any one of embodiments 1-6 and 8-17, wherein the inletflow face defines a taper for at least a portion of the axial flow facelength from the first end towards the second end.

Embodiment 8

The system of any one of embodiments 1-7 and 9-17, wherein the taperincreases for at least a portion of the axial flow face length from thefirst end towards the second end.

Embodiment 9

The system of any one of embodiments 1-8 and 10-17, wherein the tapercontinuously changes along the axial flow face length from the first endtowards the second end.

Embodiment 10

The system of any one of embodiments 1-9 and 11-17, wherein the tapercontinuously increases along the axial flow face length from the firstend towards the second end.

Embodiment 11

The system of any one of embodiments 1-10 and 12-17, wherein the firstsheet of filter media is a facing sheet and the second sheet of filtermedia is a fluted sheet.

Embodiment 12

The system of any one of embodiments 1-11 and 13-17, wherein the firstsheet of filter media and the second sheet of filter media define acoiled configuration about a z-axis extending in the axial direction.

Embodiment 13

The system of any one of embodiments 1-12 and 14-17, further comprising:

-   a rod extending centrally through the filter assembly, the rod    having a proximal end positioned towards the outlet flow face and a    distal end positioned towards the inlet flow face; and-   a rod receptacle defined by the second end of the housing, wherein    the rod receptacle is configured to receive a distal end of the rod.

Embodiment 14

The system of any one of embodiments 1-13 and 15-17, wherein the distalend of the rod defines a handle.

Embodiment 15

The system of any one of embodiments 1-14 and 16-17, wherein the filterassembly has a circular cross-section.

Embodiment 16

The system of any one of embodiments 1-15 and 17, wherein the filterassembly comprises: a plurality of first sheets of filter media and aplurality of second sheets of filter media in an alternating, stackedconfiguration; and a radial sleeve disposed about the stacked firstsheets of filter media and second sheets of filter media.

Embodiment 17

The system of any one of embodiments 1-16, wherein the housing inlet isdefined towards the first end of the housing.

Description of Exemplary Filter Assembly Embodiments for Use in aTwo-Stage Separator System of the Current Technology

Any of the following exemplary filter assemblies can be incorporated ina two-stage separator system as described herein:

Embodiment 1

A filter assembly comprising:

-   a first sheet of filter media and a second sheet of filter media    mutually defining a first plurality of flutes, a first flow face on    a first end of the filter assembly, and a second flow face on an    opposite, second end of the filter assembly,-   wherein each of the first plurality of flutes defines a distance    from the first flow face to the second flow face and each of the    first plurality of flutes defines a flute opening at the first flow    face and a flute closure towards the second flow face, where a first    flute of the first plurality of flutes defines a first flute    distance and a second flute of the first plurality of flutes defines    a second flute distance, and wherein the first flute distance and    the second flute distance differ by greater than 2 mm.

Embodiment 2

The filter assembly of one of embodiments 1 and 3-17, wherein the firstsheet of filter media and the second sheet of filter media arediscontinuous.

Embodiment 3

The filter assembly of one of embodiments 1-2 and 4-17, wherein thefirst sheet of filter media and the second sheet of filter media arecontinuous and separated by a fold.

Embodiment 4

The filter assembly of one of embodiments 1-3 and 5-17, wherein theflute closure is adjacent to the second flow face.

Embodiment 5

The filter assembly of one of embodiments 1-4 and 6-17, furthercomprising a third sheet of filter media, wherein the third sheet offilter media and the second sheet of filter media mutually define asecond plurality of flutes, the first flow face, and the second flowface, wherein each of the second plurality of flutes extends from thefirst flow face to the second flow face and each of the second pluralityof flutes defines a flute opening at the second flow face and a fluteclosure towards the first flow face.

Embodiment 6

The filter assembly of one of embodiments 1-5 and 7-17, wherein thesecond plurality of flutes comprises a third flute defining a thirdflute distance from the first flow face to the second flow face, whereinthe third flute distance differs from the first flute distance and thesecond flute distance by greater than 2 mm.

Embodiment 7

The filter assembly of one of embodiments 1-6 and 8-17, wherein thefirst plurality of flutes comprises a third flute defining a third flutedistance, wherein the third flute distance differs from the first flutedistance and the second flute distance by greater than 2 mm.

Embodiment 8

The filter assembly of one of embodiments 1-7 and 9-17, wherein thefirst flute distance differs from the second flute distance by at least5 mm.

Embodiment 9

The filter assembly of one of embodiments 1-8 and 10-17, wherein thefirst flute distance differs from the second flute distance by 3 mm to20 mm.

Embodiment 10

The filter assembly of one of embodiments 1-9 and 11-17, wherein thefirst flute distance differs from the second flute distance by at least8 mm.

Embodiment 11

The filter assembly of one of embodiments 1-10 and 12-17, wherein thefirst flute distance differs from the second flute distance by at least15 mm.

Embodiment 12

The filter assembly of one of embodiments 1-11 and 13-17, wherein thefirst flow face and the second flow face are non-parallel.

Embodiment 13

The filter assembly of one of embodiments 1-12 and 14-17, wherein atleast one of the first flow face and the second flow face is non-planar.

Embodiment 14

The filter assembly of one of embodiments 1-13 and 15-17, wherein atleast one of the first flow face and the second flow face is recessed.

Embodiment 15

The filter assembly of one of embodiments 1-14 and 16-17, wherein atleast one of the first flow face and the second flow face is planar.

Embodiment 16

The filter assembly of one of embodiments 1-15 and 17-17, wherein thefirst flow face and the second flow face are both non-planar.

Embodiment 17

The filter assembly of one of embodiments 1-16 and 18, wherein the firstsheet is a fluted sheet of filter media and the second sheet is a facingsheet of filter media.

Embodiment 18

The filter assembly of one of embodiments 1-17, wherein both the firstsheet and the second sheet are fluted sheets of filter media.

Embodiment 19

A filter assembly comprising: filter media defining a coiledconfiguration about a z-axis, wherein:

-   -   the filter media defines a first flow face, a second flow face        and a plurality of flutes extending from the first flow face to        the second flow face, and    -   the plurality of flutes comprises a first flute defining a first        flute distance between the first flow face and the second flow        face and a second flute defining a second flute distance between        the first flow face and the second flow face, wherein the first        flute distance differs from the second flute distance by greater        than 2 mm.

Embodiment 20

The filter assembly of one of embodiments 19 and 21-32, wherein thesecond flow face is non-parallel to the first flow face.

Embodiment 21

The filter assembly of one of embodiments 19-20 and 22-32, wherein thefirst flow face is non-planar and the second flow face is planar.

Embodiment 22

The filter assembly of one of embodiments 19-21 and 23-32, wherein thefirst flow face in non-planar and the second flow face is non-planar.

Embodiment 23

The filter assembly of one of embodiments 19-22 and 24-32, wherein oneof the first flow face and the second flow face is recessed.

Embodiment 24

The filter assembly of one of embodiments 19-23 and 25-32, comprising afirst sheet of filter media and a second sheet of filter media adjacentto the first sheet of filter media, wherein the first sheet and thesecond sheet defines a coiled configuration about the z-axis and thefirst sheet and the second sheet mutually define the plurality offlutes.

Embodiment 25

The filter assembly of one of embodiments 19-24 and 26-32, wherein thefirst sheet and the second sheet are discontinuous.

Embodiment 26

The filter assembly of one of embodiments 19-25 and 27-32, wherein thefirst sheet and the second sheet are continuous and separated by a foldthat defines the second flow face.

Embodiment 27

The filter assembly of one of embodiments 19-26 and 28-32, wherein thefirst sheet of filter media has a first width defined by the first flowface and the second flow face and the second sheet of filter media has asecond width defined by the first flow face and the second flow face andthe first width differs from the second width by greater than 2 mm.

Embodiment 28

The filter assembly of one of embodiments 19-27 and 29-32, wherein thefirst sheet of filter media is a fluted sheet and the second sheet offilter media is a facing sheet.

Embodiment 29

The filter assembly of one of embodiments 19-28 and 32-32, wherein thefirst flute distance differs from the second flute distance by at least5 mm.

Embodiment 30

The filter assembly of one of embodiments 19-29 and 31-32, wherein thefirst flute distance differs from the second flute distance by 3 mm to20 mm.

Embodiment 31

The filter assembly of one of embodiments 19-30 and 32, wherein thefirst flute distance differs from the second flute distance by at least8 mm.

Embodiment 32

The filter assembly of one of embodiments 19-31, wherein the first flutedistance differs from the second flute distance by at least 15 mm.

Embodiment 33

A panel filter assembly comprising:

-   a plurality of sheets of filter media in a stacked configuration    mutually defining a first flow face, a second flow face, and a    plurality of flutes extending from the first flow face to the second    flow face, wherein:-   the plurality of sheets of filter media defines a regularly    alternating pattern of first flute layers and second flute layers,    where each of the first layers defines a first layer distance    between the first flow face and the second flow face and each of the    second layers defines a second layer distance between the first flow    face and the second flow face, and-   the first layer distance and the second layer distance differ by    greater than 2 mm.

Embodiment 34

The panel filter assembly of one of embodiments 33 and 35-48, whereineach of the plurality of flutes defines a flute opening and a fluteclosure.

Embodiment 35

The panel filter assembly of one of embodiments 33-34 and 36-48, whereineach of the first layers and second layers is defined by a fluted sheetand an adjacent facing sheet.

Embodiment 36

The panel filter assembly of one of embodiments 33-35 and 37-48, whereineach fluted sheet and facing sheet in each flute layer definessubstantially equal distances between the first flow face and the secondflow face.

Embodiment 37

The panel filter assembly of one of embodiments 33-36 and 38-48, whereineach fluted sheet and facing sheet in at least one flute layer definesdistances between the first flow face and the second flow face thatdiffer by greater than 2 mm.

Embodiment 38

The panel filter assembly of one of embodiments 33-37 and 39-48, whereineach of the first layers and second layers is defined by two adjacentfluted sheets of filter media.

Embodiment 39

The panel filter assembly of one of embodiments 33-38 and 40-48, whereinthe plurality of sheets of filter media are discontinuous.

Embodiment 40

The panel filter assembly of one of embodiments 33-39 and 41-48, whereinthe plurality of sheets of filter media are continuous and separated bya first set of folds forming the first flow face and a second set offolds forming the second flow face.

Embodiment 41

The panel filter assembly of one of embodiments 33-40 and 42-48, whereinthe plurality of sheets of filter media further defines a regularlyalternating pattern of third flute layers, where each third flute layerhas a third layer distance between the first flow face and the secondflow face, wherein the third layer distance differs from the first layerdistance and the second layer distance by greater than 2 mm.

Embodiment 42

The panel filter assembly of one of embodiments 33-41 and 43-48, whereinthe plurality of sheets of filter media further defines a regularlyalternating pattern of fourth flute layers, where each fourth flutelayer has a fourth layer distance between the first flow face and thesecond flow face, wherein the fourth layer distance differs from thefirst layer distance, the second layer distance, and the third layerdistance by greater than 2 mm.

Embodiment 43

The panel filter assembly of one of embodiments 33-42 and 44-48, whereinthe second flow face is planar.

Embodiment 44

The panel filter assembly of one of embodiments 33-43 and 45-48, whereinthe first flow face and the second flow face are non-planar.

Embodiment 45

The panel filter assembly of one of embodiments 33-44 and 46-48, whereinthe first layer distance differs from the second layer distance by atleast 5 mm.

Embodiment 46

The panel filter assembly of one of embodiments 33-45 and 47-48, whereinthe first layer distance differs from the second layer distance by 3 mmto 20 mm.

Embodiment 47

The panel filter assembly of one of embodiments 33-46 and 48, whereinthe first layer distance differs from the second layer distance by atleast 8 mm.

Embodiment 48

The panel filter assembly of one of embodiments 33-47, wherein the firstlayer distance differs from the second layer distance by at least 14 mm.

Embodiment 49

A filter assembly comprising:

-   a first sheet of filter media and a second sheet of filter media    mutually defining a first plurality of flutes, a first flow face,    and a second flow face, wherein-   each of the first plurality of flutes extends from the first flow    face to the second flow face,-   each of the first plurality of flutes defines a flute opening at the    first flow face and a flute closure towards the second flow face,    and-   at least one of the first flow face and the second flow face is    recessed.

Embodiment 50

The filter assembly of one of embodiments 49 and 51-62, wherein thefirst sheet is a fluted sheet of filter media and the second sheet is afacing sheet of filter media.

Embodiment 51

The filter assembly of one of embodiments 49-50 and 52-62, wherein boththe first sheet and the second sheet are fluted sheets of filter media.

Embodiment 52

The filter assembly of one of embodiments 49-51 and 53-62, wherein theflute closure is adjacent to the second flow face.

Embodiment 53

The filter assembly of one of embodiments 49-52 and 54-62, furthercomprising a third sheet of filter media, wherein the third sheet offilter media and the second sheet of filter media mutually define asecond plurality of flutes, the first flow face, and the second flowface, wherein each of the second plurality of flutes extends from thefirst flow face to the second flow face and each of the second pluralityof flutes defines a flute opening at the second flow face and a fluteclosure towards the first flow face.

Embodiment 54

The filter assembly of one of embodiments 49-53 and 55-62, wherein thefirst plurality of flutes has a first flute defining a first flutedistance between the first flow face and the second flow face and asecond flute defining a second flute distance between the first flowface and the second flow face, and the second plurality of flutes has athird flute defining a third flute distance between the first flow faceand the second flow face, and each of the first flute distance, secondflute distance, and third flute distance differ by greater than 2 mm.

Embodiment 55

The filter assembly of one of embodiments 49-54 and 56-62, wherein thefilter assembly is a panel filter.

Embodiment 56

The filter assembly of one of embodiments 49-55 and 57-62, wherein thefirst sheet of filter media and the second sheet of filter media definea coiled configuration about a z-axis.

Embodiment 57

The filter assembly of one of embodiments 49-56 and 58-62, wherein thefirst sheet of filter media and the second sheet of filter media arecontinuous and separated by a fold that defines the second flow face.

Embodiment 58

The filter assembly of one of embodiments 49-57 and 59-62, wherein afirst flute of the first plurality of flutes defines a first flutedistance between the first flow face and the second flow face and asecond flute of the first plurality of flutes defines a second flutedistance between the first flow face and the second flow face, and thefirst flute distance differs from the second flute distance by greaterthan 2 mm.

Embodiment 59

The filter assembly of one of embodiments 49-58 and 60-62, wherein thefirst flow face and the second flow face are both non-planar.

Embodiment 60

The filter assembly of one of embodiments 49-59 and 61-62, wherein thefirst sheet and the second sheet are discontinuous.

Embodiment 61

The filter assembly of one of embodiments 49-60 and 62, wherein thefirst flow face is opposite the second flow face relative to the filterassembly.

Embodiment 62

The filter assembly of one of embodiments 49-61, wherein the pluralityof flutes are parallel.

Embodiment 63

A panel filter assembly comprising:

-   a plurality of stacked sheets of filter media each having a width    extending in a direction parallel to an x-axis and a length    extending in a direction parallel to a z-axis, wherein:    -   the plurality of sheets of filter media are stacked in a        direction parallel to a y-axis,    -   the plurality of sheets of filter media define a plurality of        flutes, a first flow face, and a second flow face,    -   each of the plurality of flutes defines a flute opening at the        first flow face and a flute closure towards the second flow        face,    -   a first flute of the plurality of flutes defines a first flute        distance between the first flow face and the second flow face, a        second flute of the plurality of flutes defines a second flute        distance between the first flow face and the second flow face,        and a third flute of the plurality of flutes defines a third        flute distance between the first flow face and the second flow        face, the second flute is adjacent the first flute in an x-axis        direction, and the third flute is positioned relative to the        first flute in a y-axis direction, and    -   the first flute distance differs from the second flute distance        by greater than 2 mm and the first flute distance differs from        the third flute distance by greater than 2 mm.

Embodiment 64

The panel filter assembly of one of embodiments 63 and 65-76, whereinthe plurality of stacked sheets of filter media are discontinuous.

Embodiment 65

The panel filter assembly of one of embodiments 63-64 and 66-76, whereinthe plurality of stacked sheets of filter media are continuous andseparated by folds.

Embodiment 66

The panel filter assembly of one of embodiments 63-65 and 67-76, whereinfirst flute distance, the second flute distance, and the third flutedistance differ by greater than 2 mm.

Embodiment 67

The panel filter assembly of one of embodiments 63-66 and 68-76, whereinat least one of the first flow face and the second flow face isnon-planar.

Embodiment 68

The panel filter assembly of one of embodiments 63-67 and 69-76, whereinat least one of the first flow face and the second flow face isrecessed.

Embodiment 69

The panel filter assembly of one of embodiments 63-68 and 70-76, whereinthe first flow face and the second flow face are both non-planar.

Embodiment 70

The panel filter assembly of one of embodiments 63-69 and 71-76, whereinthe first flow face and the second flow face are non-parallel.

Embodiment 71

The panel filter assembly of one of embodiments 63-70 and 72-76, whereinthe first flute distance differs from the second flute distance and thethird flute distance by at least 5 mm.

Embodiment 72

The panel filter assembly of one of embodiments 63-71 and 73-76, whereinthe first flute distance differs from the second flute distance and thethird flute distance by 3 mm to 20 mm.

Embodiment 73

The panel filter assembly of one of embodiments 63-72 and 74-76, whereinthe first flute distance differs from the second flute distance and thethird flute distance by at least 8 mm.

Embodiment 74

The panel filter assembly of one of embodiments 63-73 and 75-76, whereinthe first flute distance differs from the second flute distance and thethird flute distance by at least 15 mm.

Embodiment 75

The panel filter assembly of one of embodiments 63-74 and 76, whereinthe plurality of stacked sheets of filter media comprise alternatingfluted sheets of filter media and facing sheets of filter media.

Embodiment 76

The panel filter assembly of one of embodiments 63-75, wherein each ofthe plurality of stacked sheets of filter media are fluted sheets offilter media.

Embodiment 77

A filter assembly comprising:

-   filter media defining a plurality of flutes, a first edge defining a    first flow face, and a second flow face opposite the first flow face    relative to the filter assembly, wherein:-   each of the plurality of flutes defines a flute opening at the first    flow face and a flute closure towards the second flow face, and-   the plurality of flutes comprises at least one flute defining a    flute opening that is non-planar.

Embodiment 78

The filter assembly of one of embodiments 77 and 79-90, wherein thefilter media comprises a plurality of sheets of filter media in astacked configuration.

Embodiment 79

The filter assembly of one of embodiments 77-78 and 80-90, wherein theplurality of sheets of filter media comprise alternating fluted sheetsof filter media and facing sheets of filter media.

Embodiment 80

The filter assembly of one of embodiments 77-79 and 81-90, wherein theplurality of sheets of filter media are fluted sheets of filter media.

Embodiment 81

The filter assembly of one of embodiments 77-80 and 82-90, wherein thefilter media comprises a first sheet of filter media and a second sheetof filter media in a coiled configuration about a z-axis.

Embodiment 82

The filter assembly of one of embodiments 77-81 and 83-90, wherein thefirst sheet of filter media is a fluted sheet and the second sheet offilter media is a facing sheet.

Embodiment 83

The filter assembly of one of embodiments 77-82 and 84-90, wherein thefilter assembly is a panel filter.

Embodiment 84

The filter assembly of one of embodiments 77-83 and 85-90, wherein thefirst flute of the plurality of flutes defines a first flute distancebetween the first flow face and the second flow face and a second fluteof the plurality of flutes defines a second flute distance between thefirst flow face and the second flow face, and the first flute distancediffers from the second flute distance by greater than 2 mm.

Embodiment 85

The filter assembly of one of embodiments 77-84 and 86-90, wherein thefirst flute distance differs from the second flute distance by at least5 mm.

Embodiment 86

The filter assembly of one of embodiments 77-85 and 87-90, wherein thefirst flute distance differs from the second flute distance by 3 mm to20 mm.

Embodiment 87

The filter assembly of one of embodiments 77-86 and 88-90, wherein thefirst flute distance differs from the second flute distance by at least8 mm.

Embodiment 88

The filter assembly of one of embodiments 77-87 and 89-90, wherein thefirst flute distance differs from the second flute distance by at least15 mm.

Embodiment 89

The filter assembly of one of embodiments 77-88 and 90, wherein thefirst flow face and the second flow face are both non-planar.

Embodiment 90

The filter assembly of one of embodiments 77-89, wherein the fluteclosure is adjacent the second flow face.

Embodiment 91

A filter assembly comprising:

-   a first sheet of filter media and a second sheet of filter media    mutually defining a first plurality of flutes, a first flow face,    and a second flow face, wherein    -   each of the first plurality of flutes extends from the first        flow face to the second flow face,    -   each of the first plurality of flutes defines a flute opening at        the first flow face and a flute closure towards the second flow        face,    -   the first flow face and the second flow face are planar, and    -   the first flow face is non-parallel to the second flow face.

Embodiment 92

The filter assembly of one of embodiments 91 and 93-103, wherein thefirst sheet is a fluted sheet of filter media and the second sheet is afacing sheet of filter media.

Embodiment 93

The filter assembly of one of embodiments 91-92 and 94-103, wherein boththe first sheet and the second sheet are fluted sheets of filter media.

Embodiment 94

The filter assembly of one of embodiments 91-93 and 95-103, wherein theflute closure is adjacent to the second flow face.

Embodiment 95

The filter assembly of one of embodiments 91-94 and 96-103, furthercomprising a third sheet of filter media, wherein the third sheet offilter media and the second sheet of filter media mutually define asecond plurality of flutes, the first flow face, and the second flowface, wherein each of the second plurality of flutes extends from thefirst flow face to the second flow face and each of the second pluralityof flutes defines a flute opening at the second flow face and a fluteclosure towards the first flow face.

Embodiment 96

The filter assembly of one of embodiments 91-95 and 97-103, wherein thefirst plurality of flutes has a first flute defining a first flutedistance between the first flow face and the second flow face and asecond flute defining a second flute distance between the first flowface and the second flow face, and the second plurality of flutes has athird flute defining a third flute distance between the first flow faceand the second flow face, and each of the first flute distance, secondflute distance, and third flute distance differ by greater than 2 mm.

Embodiment 97

The filter assembly of one of embodiments 91-96 and 98-103, wherein thefilter assembly is a panel filter.

Embodiment 98

The filter assembly of one of embodiments 91-97 and 99-103, wherein thefirst sheet of filter media and the second sheet of filter media definea coiled configuration about a z-axis.

Embodiment 99

The filter assembly of one of embodiments 91-98 and 100-103, wherein afirst flute of the first plurality of flutes defines a first flutedistance between the first flow face and the second flow face and asecond flute of the first plurality of flutes defines a second flutedistance between the first flow face and the second flow face, and thefirst flute distance differs from the second flute distance by greaterthan 2 mm.

Embodiment 100

The filter assembly of one of embodiments 91-99 and 101-103, wherein thefirst sheet and the second sheet are discontinuous.

Embodiment 101

The filter assembly of one of embodiments 91-100 and 102-103, whereinthe first sheet and the second sheet are continuous and separated by afold.

Embodiment 102

The filter assembly of one of embodiments 91-101 and 103, wherein thefirst flow face is opposite the second flow face relative to the filterassembly.

Embodiment 103

The filter assembly of one of embodiments 91-102, wherein the firstplurality of flutes are parallel.

It should also be noted that, as used in this specification and theappended claims, the phrase “configured” describes a system, apparatus,or other structure that is constructed to perform a particular task oradopt a particular configuration. The word “configured” can be usedinterchangeably with similar words such as “arranged”, “constructed”,“manufactured”, and the like.

All publications and patent applications in this specification areindicative of the level of ordinary skill in the art to which thistechnology pertains. All publications and patent applications are hereinincorporated by reference to the same extent as if each individualpublication or patent application was specifically and individuallyindicated by reference. In the event that any inconsistency existsbetween the disclosure of the present application and the disclosure(s)of any document incorporated herein by reference, the disclosure of thepresent application shall govern.

This application is intended to cover adaptations or variations of thepresent subject matter. It is to be understood that the abovedescription is intended to be illustrative, and not restrictive, and theclaims are not limited to the illustrative embodiments as set forthherein.

What is claimed is:
 1. A two-stage separator system comprising: ahousing extending between a first end and a second end, the housingdefining a housing inlet, a separator outlet towards the second end, anda filtration outlet on the first end; and a filter assembly having afirst sheet of filter media coupled to a second sheet of filter mediamutually defining a plurality of flutes extending in an axial direction,the filter assembly defining an inlet flow face and an outlet flow face,wherein the filter assembly is disposed in the housing and coupled tothe housing about the filtration outlet such that the outlet flow faceis in fluid communication with the filtration outlet, and wherein theinlet flow face has an axial flow face length.
 2. The system of claim 1,wherein a radial distance is defined between the inlet flow face and thehousing, wherein the radial distance increases for at least a portion ofthe axial flow face length from the first end towards the second end. 3.The system of claim 1, wherein the filter assembly has an outer radialbarrier surface extending axially from the filtration outlet beyond thehousing inlet.
 4. The system of claim 1, wherein the filter assembly hasan outer radial barrier surface having an axial length from the outletflow face towards the inlet flow face that is greater than or equal toan axial distance from the filtration outlet to a distal end of thehousing inlet.
 5. The system of claim 1, wherein the housing inletdefines an airflow pathway that is tangential to an outer radial barriersurface of the filter assembly.
 6. The system of claim 5, wherein atleast a portion of the outer radial barrier surface is defined by thefirst sheet of filter media.
 7. The system of claim 1, wherein the inletflow face defines a taper for at least a portion of the axial flow facelength from the first end towards the second end.
 8. The system of claim7, wherein the taper increases for at least a portion of the axial flowface length from the first end towards the second end.
 9. The system ofclaim 7, wherein the taper continuously changes along the axial flowface length from the first end towards the second end.
 10. The system ofclaim 7, wherein the taper continuously increases along the axial flowface length from the first end towards the second end.
 11. The system ofclaim 1, wherein the first sheet of filter media is a facing sheet andthe second sheet of filter media is a fluted sheet.
 12. The system ofclaim 1, wherein the first sheet of filter media and the second sheet offilter media define a coiled configuration about a z-axis extending inthe axial direction.
 13. The system of claim 1, further comprising: arod extending centrally through the filter assembly, the rod having aproximal end positioned towards the outlet flow face and a distal endpositioned towards the inlet flow face; and a rod receptacle defined bythe second end of the housing, wherein the rod receptacle is configuredto receive the distal end of the rod.
 14. The system of claim 13,wherein the distal end of the rod defines a handle.
 15. The system ofclaim 1, wherein the filter assembly has a circular cross-section. 16.The system of claim 1, wherein the filter assembly comprises: aplurality of first sheets of filter media and a plurality of secondsheets of filter media in an alternating, stacked configuration; and aradial sleeve disposed about the stacked first sheets of filter mediaand second sheets of filter media.
 17. The system of claim 1, whereinthe housing inlet is defined towards the first end of the housing.